Freshwater Fishes of Iran

Species Accounts

Description
and
Petromyzontidae to Clupeidae

Revised:  10 April 2016

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Description

The species dealt with here in detail have all been recorded from Iran and confirmed by specimens. Mention is also made of other species which occur on the borders of Iran or in drainage basins shared with Iran. These have no valid Iranian record but may eventually be found in that country. The listing here is selective from other papers by me on neighbouring countries as a number of species are unlikely to enter Iranian waters because their distributions are too remote, e.g. Cobitis elazigensis from the Tigris-Euphrates basin at Elazig in Turkey or too restricted, e.g. Typhlogarra widdowsoni from a cave in Iraq (see Coad, 1991b). Coad (1995a) gives a more complete listing of species found in waters neighbouring Iran. The most recent checklist on this fauna is by Esmaeili et al. (2010).

The definition of freshwater here includes the southern Caspian Sea which is at one-third seawater and has both nominally marine and freshwater species in its fauna.

The choice of introduced species to include in the Species Accounts is somewhat arbitrary. Soviet authorities introduced a number of species into the Caspian Sea and its tributaries and some of these became well established, spreading to Iranian waters, e.g. Liza aurata and Liza saliens, now commercially important. Other species did not become established but the potential for spread was there and so they are mentioned briefly in the Species Accounts. In northeastern Iran, the Tedzhen River flows into Turkmenistan and a number of exotic species are known from this former Soviet republic (see Aliev et al., 1988; Shakirova and Sukhanova, 1994; Sal'nikov, 1995). I have listed here only ones reported from the Tedzhen River basin and its reservoirs. The Tedzhen (Hari Rud in Iran) connects with the Karakum Canal which harbours a number of exotics as well as species from the Amu Darya. These may be able to colonise Iranian waters should they reach the Tedzhen River but are not included here in the absence of definite records.

A paper in Farsi by Farid-Pak (1957) records the grayling, Thymallus thymallus (Linnaeus, 1758), the lacustrine smelt Osmerus eperlamus eperlamus (sic) m. sprinchus (sic) (= Osmerus eperlanus eperlanus morpha spirinchus Pallas, 1814) and the sculpin Cottus gobio koshewnikowi Grazianov, 1907 from the Caspian coast of Iran but the first two species are distributed in waters remote from Iran and the last has not been recorded south of the Caucasus (Abdurakhmanov, 1962; Abbasov, 1980). They are assumed here to be misreadings of the literature and are not included in the species list.

Some marine species penetrate the fresh waters of southern Iran from the Persian Gulf and Sea of Oman. These species are included in a Marine List under Checklist in the Introduction. They are not included in keys but more detailed descriptions of these fishes can be found in the literature listed in the Bibliography such as Blegvad and Lppenthin (1944), Randall et al. (1978), Kuronoma and Abe (1986) and Assadi and Dehqani Posterudi (1997). Certain marine species do, however, spend a significant part of their life cycle in brackish to fresh water and are given full accounts as freshwater fishes, e.g. Carcharhinus leucas and Tenualosa ilisha. Choice of other marine species to be given a full treatment is dependent on frequency of capture, residence time and distance from the sea.

Coad (1991b; 2010) and the website Freshwater Fishes of Iraq give a list of marine species known from the Tigris-Euphrates basin but these are mostly records from the Shatt al Arab and Hawr al Hammar in Iraq which are under tidal influence. Hussain et al. (1989) give an account of seasonal fluctuations in species composition in the Shatt al Arab, Iraq. Little or nothing is known of the biology of these species in fresh and brackish waters. They are listed here to give an idea of the diversity of species which could be found in Khuzestan and in rivers along the Persian Gulf coast but are not covered in detail unless verified for Iran. Al-Daham and Yousif (1990) list additional species in an Iraqi estuary but do not distinguish the marine species which entered purely fresh water.

Taxonomy and systematics are active disciplines and scientific names of families, genera and species recognised from Iran can change. Older literature will be under the former name and searches for information in such fields as ecology should take this into account. These are described under the appropriate taxon but some significant changes, relevant to the Iranian species only, can be simply summarised as:-

Family changes:-

Cobitidae becomes Cobitidae and Nemacheilidae (the latter formerly Balitoridae).

Gadidae becomes Lotidae.

Generic changes:-

Caspialosa becomes Alosa.

Barbus becomes Barbus, Carasobarbus, Kosswigobarbus, Luciobarbus, Mesopotamichthys, and Tor.

Chalcalburnus becomes Alburnus.

Gobio becomes Gobio and Romanogobio.

Leuciscus becomes Petroleuciscus and Squalius.

Cobitis becomes Cobitis and Sabanejewia.

Nemacheilus becomes Ilamnemacheilus, Metaschistura, Oxynoemacheilus, Paracobitis, Paraschistura, Seminemacheilus, and Triplophysa.

Lebias becomes Aphanius.

Neogobius becomes Babka, Chasar, Neogobius, and Ponticola.

The Species Accounts are arranged by family after Nelson (2006). A higher classification can be found in the Checklist in the Introduction. Each Species Account is comprised of the following parts:

a) Illustration

The species is illustrated by a line drawing which is accurate in respect of body shape, number, position and shape of fins, scales and other structures. This drawing is usually a composite one, based on both a variety of published illustrations and on specimens.

Further illustrations are from various sources as indicated, are of varying quality and format, and may include colour and black and white photographs.

Diagrams may also be found in the Keys to illustrate characters not apparent in the main drawings, such as mouth structure.

b) Map

Distributions are summarized in the form of a map. Often two maps are given, one for the whole of Iran and one zooming in on distribution if restricted to a particular part of the country. The maps are from a world map layer provided by Demis bv (www.demis.nl), accessed through http://linuxgurrl.agr.ca/mapdata/itis/itisrosa.php.

Maps must be examined in conjunction with the text Distribution (see below). Map points are are a reflection of adequately documented museum collections and literature. As such they reflect catchability, ease of identification, rarity, size (large species not as easily preserved in museums as small ones but perhaps better documented, even if only in general), field work, available nets and other equipment, contiguity to research stations and universities, road accessibility, commercial interest, research interests, and so on. However, while bearing all these variables in mind and reading the Distribution summary critically, it is possible to gain a picture of fish distributions and objective rarity of species. Other sources of distributional data are field notes (principally mine and those of V. D. Vladykov) and sight and field records transmitted to me verbally by sources judged to be authoritative.

Note that many of these localities were ascertained in pre-GPS days from maps of varying quality and literature requiring some careful interpretation. Maps available in the field did not always match maps examined later and once I was lost for a whole day. Zooming in reduces accuracy proportionately.

Each symbol may represent more than one record because of the scale of the map or because of repeated visits to the same locality. Localities have not been sampled on a regular basis so population trends cannot be given. The general distribution in Iran and elsewhere is also given textually as outlined below.

The best records are those based on collections in a museum as these can be re-examined should any questions arise about identity and field data notes can be re-assessed for accuracy. However, the data associated with many museum collections are too vague or too contradictory to be included on maps with a locality symbol.

Criteria for inclusion of literature mapping records are as follows:-

1. Accurate identification (e.g. on geographical grounds; uniqueness of species so it could not possibly be anything else; lack of systematic/taxonomic confusion; distinctive characters cited in the text, drawn or photographed; assessed competence of author in identification),

2. Accurate latitude-longitude data. Latitude-longitude may be given by the author or derived by me from the literature based on maps and gazetteers, unique locality names, and my field experience close in time to when the material was recorded (road/river crossings have changed in some areas with new construction after the Islamic Revolution). One exception in accurate latitude-longitude data is that of migratory fish - if reported from a named river then the river mouth can be recorded since the fish pass this point on their migration (but few works mention the extent of upriver migration so no upper limit can be deduced; when an upper limit is given this is spot mapped; then the species is theoretically present in a continuous distribution from mouth to upper limit along the river but this distribution is not filled in and this presence along the river must be assumed from the known migratory habit).

Criteria for exclusion of literature mapping records are as follows:-

1. Generalised localities are not accepted, e.g. Safid River is not accepted since the actual locality along this river is unknown (except migratory fish - see above); landing ports, fish markets and fish farms are not included as localities unless the fish capture site or release site is known,

2. Localities with non-unique names, e.g. Hosseynabad, a common name for many villages; Shur River, a common name for any brackish stream, unless these have accurate qualifying data,

3. Descriptions with internal inconsistencies which cannot be resolved to one locality,

4. Named sites which cannot be found in a gazetteer; this is often a problem with Farsi names transliterated into various European languages with widely differing orthography,

5. Literature records which conflict with original field notes, jar labels or catalogues unless the literature explains why it differs.

Under Sources is a partial list of material examined, most with latitude-longitude. Some material was identified and is used in mapping distributions but lengths were not taken and that material is not listed. Sometimes fish were spirited away to be eaten, fell back in the river, leaped over nets, were kept by another researcher, were seen on market stalls and the source was given verbally, and so on. Collections in Sources may be annotated as "no other locality data" indicating that the collection data could not be interpreted to a latitude/longitude or was internally contradictory.

c) Scientific and Common Names

The use of scientific names is described in the Introduction. Scientific names are dynamic and can change as knowledge of the fishes increases. The ones used here are the latest available.

Common names in Farsi are given with the English translation in parentheses. Obviously some Farsi names are merely a translation from the English common name. Note however that some Iranian names are originally Arabic or Turkic in origin and I have not always been able to track their meaning. Some species have no common name and none has been advocated. Others have a common name which is applied to all members of the same genus (e.g. nemacheilid species are called mar mahi (= snake fish)) but this has not been repeated under each Species Account. The common name in Russian, Arabic, Azarbaijanian, English and from Pakistan is also given to facilitate communication and understanding; these names are in brackets.

There are often many common "book" names for Caspian Sea fishes. This is a result of the Russian designation of subspecies and other categories such as natio. The names are often based on geographical locations. These names are included here, although many of the taxa are not now recognised, as an aid to study of the literature. The names are probably not used locally. Azerbaijani names appear to follow mostly the Russian designations for these subspecies and again may not be truly local names.

The names cited as by J. J. Heckel in Arabic are also of dubious value. They are quite old, often from areas remote from Iran, and may not be in use today. A number of common names whose origin is Arabic are in use in Khuzestan however, although transmogrified into Farsi.

d) Systematics

An extensive synonymy or historical treatment of the mis-application of scientific names is not given. Some earlier names can be found in synoptic works such as Berg (1948-1949; 1949), Coad (1981d; 1985), Krupp (1985) and others. In certain cases, systematic or nomenclatorial problems remain unresolved and these are briefly discussed.

Type locality is given for species originally described from Iran or immediately adjacent waters. This type locality is given as cited in the original text description in quotes ("....") wherever possible. Some type localities are not given in quotes, e.g. middle Caspian Sea, to denote they are a general indication of where the fish was first described - this is usually applied for older literature not at hand or for fishes not described from Iran but nearby waters. The original text, jar labels or catalogues may be compared and interpreted where these are unclear, contradictory or spellings of place names have changed markedly. Most agree well between these three sources and are easily located with due allowance for variant spellings, handwriting skills and transcription errors. Disposition, number and condition of types may vary with time however. Eschmeyer's on-line "Catalog of Fishes" has disposition of types but these records are only as good as the most recent revision of the taxon concerned. Latitude and longitude are calculated for type localities in Iran wherever possible.

Note that transliteration from Russian names often gives variant spellings for authors of species names. Actual dates of publication may vary one or more years subsequent to the date on the journal or article, i.e. publication may be delayed. This may not be evident from an examination of the article but may be known to the author or others familiar with the situation. This has not always been clearly set down in print and accounts for varying publication dates in different sources.

The disposition and condition of type material is given where known along with catalogue numbers. Museum acronyms are from Leviton et al. (1985) but these may change, notably ZIL (Zoological Institute, Leningrad, U.S.S.R.) became ZISP (Zoological Institute, St. Petersburg, Russia) and the British Museum (Natural History), London became the Natural History Museum but retained BM(NH) as its acronym. Note that knowledge of type material in museums changes as the specimens are examined over time. Not all new information is published as it is the result of in-house curatorial work and may only be available in catalogues and jar labels. The information cited here is the most recent available to me.

Subspecies and lower, non-taxonomic categories have received names. Such taxa (and non-taxa) have a narrower range of meristic characters and certain distinguishing other characters compared with the species. Ranges and descriptions apply to the species as a whole, since many subspecies appear to be ill-founded where they have been studied in more detail, and indeed some species are not distinct but members of a wide-ranging and variable species. Certain subspecies may be valid, or their status is undetermined by recent study, and characters for these are given separately, either here or in Key characters or Morphology.

e) Key characters

The characters detailed here will separate the species from any Iranian freshwater fish. These characters (and the keys) should not be used to identify species from countries bordering Iran as they are specific to Iran.

f) Morphology

Under this heading are described a number of features which add to the key characters in describing the fish. Morphometric characters are not often used since the shape of body parts can be seen in the drawing and such characters vary greatly with sex and size in contrast to meristic characters. The accurate explication of morphometric characters depends on comparative statistics and is beyond the scope of this work. The assessment of variation between adults and juveniles or between geographical localities is limited by material and its presentation here by space.

The chief characters summarised here are meristic or countable characters. These include counts of scale, fin rays, vertebrae, gill rakers, and teeth. They are summarised as ranges based on literature sources (including my own data where this expands ranges). In certain cases literature data is extensive and swamps the few specimens available from Iranian waters. The literature ranges give an indication of how variable a species may be in a given character; data on a few Iranian specimens would give a misleading picture of potential variation which future students of Iranian fishes may find. Counts from Iranian specimens made by me are given with frequency in parentheses, e.g. dorsal fin branched rays 7(3), 8(34), 9(5) indicates that 3 fish had 7 branched dorsal fin rays, 34 fish had 8 branched rays and 5 fish had 9 branched rays.

g) Sexual dimorphism

Males and females often differ markedly in appearance, whether in colour, body proportions or in structural features and these are detailed here to obviate misidentifications.

h) Colour

The colour patterns of fresh and preserved specimens including males and females, young and adult, and spawning and non-spawning individuals are given where known. Colour can be a key character in determining the species but is also variable and should be treated with care in identifications. Some fish change colour to match their background or pale in response to a threat. Fish from muddy waters in Iran are often washed out and greyish in colour. Immersion in ice water enhances the colour patterns and some of this is retained in preservative.

i) Size

The maximum reported size is recorded as total length or standard length (if not specified then the source did not indicate which length was measured) and weight where known. These measures are not restricted to Iranian specimens since sample sizes are small for some species and would give a false picture of maximum size.

j) Distribution

This section summarises distribution for the whole range of the species both within Iran and the rest of the world. Within Iran the general distribution is given. The detailed mapped distributions are based on collections or literature with adequate data (see above under Map). Some literature and museum records are given simply as, e.g. "Safid River", which cannot be mapped accurately but can be cited in this section. Some literature records are included here but not every locality based on my field collections as these are summarised on maps. Not every river mentioned in the literature is listed here, as common species are assumed to be widely distributed within a basin; generally only those major rivers or general localities that are in basins without a mapped distribution are cited.

k) Zoogeography

The relationships of the species, its origins and movements in the past are given here, where this has been determined.

l) Habitat

The type of habitat favoured by the species is outlined and includes such factors as altitude, substrate, temperature, salinity, oxygen, flow regime, pH, vegetation, turbidity, pollution resistance, etc. There are few detailed studies of habitat requirements for many species: some can be deduced from morphology. Field data can give a partial picture but are often limited to one time measurements of seasonal and daily variables such as temperature which are necessarily of restricted value. Colour illustrations of habitats are included where available.

m) Age and growth

This section, and the following two sections, either have no information or masses of information. The Caspian Sea basin species are often widely known and have books and numerous papers written about them. There is also a vast "Soviet" literature on some of these species but I did not have the time nor the resources to digest it all. Here only brief summaries can be given and it is not always clear whether the Iranian populations, often at the southern edge of the species range, or recognised as a distinct subspecies, have the same general ecology as European or more northerly "Soviet" populations.

Most species outside the Caspian basin are poorly known ecologically. I have attempted to summarize what is known based on literature in particular from Iraq and Turkey where ecological studies of varying quality have been published on some of the species. Morphology can be used to gain a general picture and knowledge of related species helps.

Generally growth in fishes is fastest in the youngest age groups, slowing with age and with investment in reproduction. Maximum age varies considerably, some small species living only a few years while others are much larger and are reputed to live longer than people. Conventionally, age may be represented by a number then the + sign, e.g. 0+ = a fish in its first year of life, less than one year old; 6+ = a fish between 6 and 7 years old.

n) Food

Diet is reported from literature studies and from brief examination of gut contents by me. Diet varies seasonally, daily, with age, between sexes, and with changes in environmental conditions but most fish concentrate on one or a few major groups. These are scrapers, invertebrates and fishes, and rarely aquatic macrophytes.

o) Reproduction

The spawning season, migrations, egg numbers and diameters, and reproductive behaviours are recorded here. Some migratory behaviour and ages at spawning may be recorded in the the Habitats and Age and growth sections.

p) Parasites and predators

This section contains information on the parasites and predators of the species described. I have recorded only parasites known from Iranian populations. There is a more extensive literature on Iraqi populations (see Mhaisen, 1980; Coad and Al-Hassan, 1989) and on European or Caspian Sea populations (see Romanov, 1955) for species found in Iran. For eastern waters consult Moravec and Amin (1978) on Afghanistan and Mirza (1978) on Pakistan. In the absence of definite records for Iran and in the interests of saving space, I have not cited this extensive literature. Pazooki and Masoumian (2012) provide a synopsis of parasites in Iranian freshwater fishes and this extensive list (247 species) has not been integrated into the text of the present work.

There are a number of piscivorous birds in Iran (see Scott et al. (1975), Behrouzirad (2007) and general field guides) and these take fishes but there seems to be little direct observation on the fish species preferred.

q) Economic importance

Note that fishery information may be given on an annual basis but the year reads 1965-1966 or 1965/66; Iranian years start in March and run across 2 western calendar years.

r) Conservation

This section details conservation measures undertaken or needed for the species. A general survey of conservation status of native Iranian freshwater fishes is given by Coad (2000a).

s) Further work

This section gives some suggestions for knowledge gaps that should be filled.

t) Sources

This section refers to papers or synoptic works on the species in addition to those cited in the text. It should be noted that a number of synoptic works refer to several species in Iran, e.g. Berg's "Freshwater Fishes of the U.S.S.R. and adjacent countries", and these are not listed repetitively under each Species Account although they are to be found in the Bibliography. Web sites or URLs are cited as documentation of statements but it should be noted that these may become broken links and they are not continually verified as active.

Descriptions are based on Iranian specimens wherever possible but additional material from neighbouring countries has also been examined. Meristic counts, for example, are given as frequency distributions for Iranian material while general ranges for these characters are based on Iranian material, on literature and on counts of other specimens listed here briefly. Descriptions are also based on material seen in bazaars or captured in the field but not retained, and on photographs, drawings, field notes of other collectors, and verbal descriptions of other scientists.

Details on collections are on file at the Canadian Museum of Nature, Ottawa and in other institutions as recognised by their acronyms. Locality data is given in short form and the reader is referred to the website of the relevant museum for further information. Locality names are taken from U.S. Board on Geographic Names publications and these may vary from names on labels in museums. The Board names contain both conventional and local Farsi, Arabic and Turkish names of localities. I have interpreted names as best I can and have, for example, retained English names for major water bodies and towns where a strict usage would be bewildering, e.g. Harirud = Tedzhen River, Sefidrud = Safid River, Al Mawsil = Mosul, Darya-ye Mazandaran = Caspian Sea, and so on. Sometimes a collection is annotated as "no other locality data", indicating that no further details are known or localities cited could not be found on maps or in a gazetteer (and thus there is no latitude-longitude). Collections listed as uncatalogued are mostly held in the Canadian Museum of Nature and may eventually receive a catalogue number. The collections listed are those examined for morphology. Map records include these collections, other collections checked for identity and locality only, and literature sources, all kept in a database held at the Canadian Museum of Nature: these would be too lengthy to list here.
 


Petromyzontidae

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Lampreys in the family Petromyzontidae are found in cooler waters of the northern hemisphere, with a few related species in other families in the southern hemisphere. Their origins lie at least 300 million years in the past. There are about 43 lamprey species in 9 genera (Eschmeyer and Fong, 2011) with only 1 recorded from Iran.

Lampreys are jawless fishes, lacking bone in the skeleton and having 7 pairs of pore-like gill openings. The eel-like body has no pectoral or pelvic fins. There are 1 or 2 dorsal fins and a caudal fin. An anal fin-like fold develops in spawning females. The mouth is a suctorial disc armed with rows of horny teeth. There are also teeth on the tongue. The median nostril, or nasohypophyseal opening, is not connected to the mouth. There is a light-sensitive pineal organ or "third eye" behind the nostril. The skin is covered in mucus which is poisonous to fishes and humans. Lampreys are edible if the mucus is cleaned off.

Their tooth arrangement is used in classification and identification along with the number of myomeres (muscle blocks along the body). Both tooth counts and the number of cusps are used, in particular those on the supraoral lamina (bar above the "mouth", the oesophageal opening), the infraoral lamina (bar below the "mouth") and the row of teeth on both sides of the "mouth". There are various series of smaller teeth and of course teeth on the tongue. Larval lampreys lack teeth and are particularly difficult to identify and their determination often requires specialist knowledge. Characters for the larvae include counts of myomeres and pigmentation patterns.

Lampreys have an unusual life cycle. Adults die after spawning and the eggs develop into a larva, known as an ammocoete, which lacks teeth, has an oral hood, eyes covered by skin, a light-sensitive area near the tail, and is a filter-feeder while buried in mud and silt. Fleshy tentacles in the oral hood are used to extract minute organisms from the water, such as algae (desmids and diatoms) and protozoans. After several years (up to 19 but usually 7 or less), the ammocoete transforms into an adult with enlarged eyes, teeth, a different colour and pronounced dorsal fins. The body shrinks during this metamorphosis and adults are only larger than ammocoetes if they feed. The adult may be a parasite on other fishes and marine mammals, or non-feeding. Individuals of a species may or may not be parasitic and different species may be parasitic or non-parasitic. The non-parasitic species are believed to have evolved from a parasitic species so there tends to be closely related parasitic/non-parasitic species pairs.

Parasitic adults feed mostly on other fishes, attaching to their bodies by suction and using their toothed tongue to rasp through the skin and scales to take blood and tissue fragments. Prey is detected by sight but some lampreys attach to hosts during the night. Perhaps this reduces their own predation risks and enables them to approach their quiescent hosts more easily. Lampreys tend to select larger fish as these survive longer and ensure a good food supply. The flow of blood is aided by an anti-coagulant in lamprey saliva called lamphedrin which also serves to break down muscle tissue. The attack may weaken or even kill the host. Weakened fishes are more prone to diseases and the wound provides an easy path of entry for them. The fish (and marine mammal) species parasitised are varied and reflect availability in the habitat.

Marine lampreys enter fresh water to spawn and freshwater species may move into or up streams. The scientific name of the family means "stone sucker" and the adult mouth is used to hold or suck onto stones as well as on prey. This suction enables the lamprey to maintain position in fast-flowing streams when spawning and even to climb over rapids and small waterfalls. Usually spawning occurs in shallow water with a moderate current, a bottom of gravel and nearby sand and silt for the ammocoetes to live in. Either or both sexes build a nest by moving gravel around with their sucking mouths and by thrashing their bodies. A shallow depression is formed, about 0.5-1.0 metre long. Spawning often occurs in groups and several males may attach to a female with the sucking disc. The process takes several days as only a few white to yellow eggs are laid at a time. The eggs are adhesive.

Adult lampreys are usually caught when attached to a host or when spawning. Electro-shocking will force ammocoetes out of their u-shaped burrows to the surface and immobilize adults. They sometimes attach to boats and occasionally to human swimmers when their skin is cool but are easily removed, perhaps because nobody has left a lamprey on their skin long enough to see if the tongue starts rasping flesh!

Genus Caspiomyzon
Berg, 1906

This genus is characterised by having 2 dorsal fins, an oral disc narrower than the body, teeth are generally low and blunt, the supraoral lamina is small, oval and sometimes has 2 tubercles and rarely 2 teeth, the infraoral lamina has 4-6, usually 5, teeth which may be bicuspid at their tips, there are about 8 small teeth of equal size in the transverse lingual lamina, the exolaterals, anterials and posterials are strong and close together, anterior and endolateral circumorals 9-11, usually 11, and 3 long, papillose velar tentacles are present. The first illustration below shows a notch at the end of the second dorsal fin which is an error.

There is a single species in the genus found only in the Caspian Sea basin. Agnathomyzon Gratzianow, 1906 and its subgenus Haploglossa Gratzianow, 1906 are synonyms of Caspiomyzon (Eschmeyer et al., 1996).

Caspiomyzon wagneri
(Kessler, 1870)


Adult


Ammocoete


Disc

Adult, courtesy of Afshin Afzali, University of Tehran
Adult, courtesy of Afshin Afzali, University of Tehran

Adult, Shirud River,  courtesy H. Nazari
Adult, Shirud River, courtesy H. Nazari

Siardarvishan River, April 2010, courtesy of K. Abbasi
Siardarvishan River, April 2010, courtesy of K. Abbasi

Adults, Shirud River, courtesy H. Nazari
Adults, Shirud River, courtesy H. Nazari.

Disc, courtesy H. Nazari
Disc, courtesy H. Nazari

Disc, Siardarvishan River, April 2010, courtesy of K. Abbasi
Disc, Siardarvishan River, April 2010, courtesy of K. Abbasi
 

Common names

مارماهي (= mar mahi, meaning snake fish), مارماهي دهان گرد (= marmahi-ye dehangerd, meaning round mouth snake fish), mahi dehangerd, mahi dehangerd daryacheh-ye khazar or dahangerd-e-Daryaye Khazar (= Caspian Sea round mouth fish).

[ilanbaligi or xazar ilanbaligi, djilan-balux or morma in Azerbaijan; kaspiiskaya minoga or Caspian lamprey in Russian; Volga lamprey].

Systematics

The type locality of Petromyzon Wagneri is from the mouth of the Tvertsa to Astrakhan; Oka and Kama rivers and the 3 syntypes (29.0-33.0 cm) are in the Zoological Institute, St. Petersburg (ZISP 31) (Holčk, 1986). The Zoological Museum of Moscow University (ZMMU) has one syntype from the Kura River near Evlakh (P-1393) and one from the Moskva River (P-555) with P-569 from the Volga River near Kazan being lost (Pavlinov and Borissenko, 2001). The Naturhistorisches Museum Wien in 1997 had one specimen listed as "? syntype, ? paratype" (sic) under NMW 61053. Agnathomyzon (Haploglossa) caspicus Gratzianow, 1907 is a synonym.

Key characters

This is the only lamprey species in Iran, easily recognised by the absence of pectoral and pelvic fins, a round, suctorial mouth containing blunt teeth, and 7 branchial openings.

Morphology

Characters of the species are the same as the genus. Trunk myomeres number 53-68 in ammocoetes; and 68(2) or 69(1) in adults from Iran. Ginzburg (1936a) describes ammocoetes from Iran. Renaud et al. (2009) give details of the feeding apparatus. Nazari et al. (2009) found significant differences for morphometric, but not meristic, characters, between fish from the Shirud and Talar River, although a principal components analysis showed relatively high overlap. Renaud (2011) gives details of morphology.

Sexual dimorphism

Females reach larger sizes than males and have a smaller urogenital papilla. During the spawning migration, the lamprey undergoes certain morphological changes some of which have been linked to sex of the fish. The teeth become blunt, fin size increases, the dorsal fins become almost united at the base in males, and there is a change in colour. The urogenital papilla length in males increases from a mean of 1.1 mm to 4.9 mm and in females from a mean of 0.6 to 1.7 mm.

Colour

Adults are dark grey with a silvery-white belly. Spawning adults become black on the back and flanks with a grey belly covered with dark oval spots, or are an overall golden colour (Hassan Nazari, pers. comm., 28 July2011, see photo above). Ammocoetes are a pale grey to yellowish with a white belly.

Size

Attains 57.5 cm total length and 205.5 g as the adult and 13.0 cm total length as the ammocoete. After metamorphosis of the ammocoete there is a shrinkage in length, the difference between prespawning and spawning adults being on average 22.3% in Iranian samples (Renaud, 1982). There is also a small variety which measures 19-31 cm and can attain sexual maturity at 19.1 cm (forma praecox).

Distribution

Found only in the Caspian Sea and rivers draining to it, in particular the Volga where it had its largest distribution but is now known only as far as the Volgograd Reservoir; also in the Ural, Terek, and Kura rivers. It is recorded in Iran from the upper reaches of the Aras River, and from the Astara to the Gorgan River along the whole Caspian coast. Specific localities include the Aras River, Anzali Mordab and the Nahang Roga, Pir Bazar Roga, Pasikhan River and Siah Darvishan River in the Anzali region, to Kisom on the Safid River, Cheshmkelya east of the Safid River, Tajan River, Sardab River, Haraz River, Babol River, Tonekabon River, Pol-e Rud, Gorgan River, and in most large streams (Derzhavin, 1934; Holčk and Olh, 1992; Hosseinpour, 1995; Abbasi et al., 1999; Kiabi et al., 1999; Abdoli, 2000; Abdoli and Naderi, 2009). Migrations into the Babol, Gorgan and Sardab rivers are reported by Ghasempouri (1993), the Sardab and Chalus rivers by the Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran (1996), and the Shirud (Nazari and Abdoli, 2010), for example.

Zoogeography

Known only from the Caspian Sea, its relationships remain uncertain and research is ongoing (Claude B. Renaud, pers. comm., 18 May 2007).

Habitat

The habitat of this species in the southern Caspian Sea proper is unknown although some specimens have been caught in the Caspian at 600-700 m (Jolodar and Abdoli, 2004). Larvae burrow 1-2 cm into the river bottom and favour areas where current is moderate at river bends. They can also be found in the centre of rivers or in backwaters. Fine-grained sand with some ooze and detritus is preferred at all stages of larval growth but larger larvae can also be found in a silt-sand bottom with much plant debris and macrophytes. The ammocoetes select and change habitat according to sediment size as they grow. They prefer depths greater than 3 m as protection against drying out, are mostly shallower than 11 m but as deep as 22 m (Ginzburg, 1970), yet in different rivers or at different times will be concentrated in water of markedly different depths, e.g. 30-85 cm versus 6-8 m.

Spawning migrations up the Volga River used to exceed 1500 km but construction of dams now prevents this. The lamprey migrates in schools with the smaller fish arriving in estuaries first. Larger lampreys migrate more quickly and travel further. The speed varies from 1.9 to 15.9 km/day. The migration is triggered by decreasing water temperature and increasing water level. The strongest migration is reported at 6-11C. Movement upriver only occurs at night, near the surface when dark and on the bottom when the moon is out. During the day, the lampreys hide among stones. Body fat in the Volga delta was 34% but by the time the fish reached the spawning grounds upriver it had declined to 1-2%. In the Kura River of Azerbaijan, the lamprey migrates at the same time as the Caspian salmon (mahi azad, Salmo caspius) and often attaches to the opercular region of this species. The peak of this run is in December and January. The migration in the Volga takes place from the middle of September to the end of December. Migrating lampreys prefer a current velocity of 0.4-0.6 m/sec and stay close to banks and the bottom. Prespawning adults overwinter among stones or in the substrate of rivers. During winter-spring several individuals may be found coiled in a ball under stones (Askerov et al., 2001). They hardly respond to external stimuli such as noise or being handled. Transformed lampreys migrate to the Caspian Sea. Before breeding, males change colour, increase slightly in size, develop their fins, and become much more active (Askerov et al., 2001).

Nazari and Abdoli (2010) note a short fall migration in late September to October with the main migration being in spring (see below). Movement was mostly at night and involved swimming and resting attached to the concrete of a bridge used as the observation post.

Age and growth

The growth rates of metamorphosing lampreys and adults are almost unknown. Length and weight decrease but coefficient of condition increases in spawning as opposed to pre-spawning adults. The shrinkage in mean total length is 18-26%. Females are heavier than males up to about 43 cm but past this point males weigh more. There are 3 age groups of larvae in the Volga (Ginzburg, 1970), with average lengths of 3.1 cm, 6.2 cm and 10.1 cm and 2-4 age groups in the Kura. In their fourth year of life they metamorphose to adults after a downstream migration into the Caspian Sea. Adult life span is at least 1 year and 5 months. Maturity is attained in May and the beginning of June in the Volga, and from May to the end of July in the Kura River. Mature lampreys are mostly 35-41 cm in the Volga and 41-46 in the Kura River. The female lamprey dies after spawning but the male may live longer until sperm production ceases.

Nazari et al. (2010) investigated growth parameters in fish from the Shirud and Talar River. Most fish were were in the 367-369 mm length group, length-weight relationship was positive, high and significant, growth was negatively allometric, the coefficient of condition was higher in females, sex ratio was nearly equal, and growth parameters were similar in the two rivers.

Food

Abakumov (1959) maintains that this lamprey attacks Caspian salmon (Salmo caspius) based on nineteenth century observations by Kessler (1870a) and Kavraiskii (1896-1897). Lelek (1987) also considers it to be parasitic. The lampreys may only have been using Caspian salmon for transport. Certainly the teeth in this lamprey are blunt, unlike those in lamprey species known to parasitise fishes. In contrast, Holčk (1986) states that it is non-parasitic and Ghasempouri (1993) agrees. Renaud (1982) supposes that adults feed on amphipods since juvenile acanthocephalans (Corynosoma sp.) are found in prespawners. This worm has amphipods as the intermediate host. However, Holčk (1986) thinks that the acanthocephalans are swallowed while the adult lampreys are feeding on the internal organs of dead fish they scavenge. Certainly larvae of Corynosoma strumosum (perhaps correctly C. caspicum: B. Kiabi, in litt., 1994) are found only in the body cavity of fishes. Renaud et al. (2009) list it as a carrion feeder but note the well-developed buccal glands which may compensate for the blunt teeth and it may well feed on fishes. The feeding habits of the adult of this species remain to be confirmed by direct observation. Gut contents include aquatic vegetation in Iran and in the Volga delta. Migratory, transforming and spawning lampreys do not feed. The gut diameter decreases from 2.7 mm in prespawners to 1.4 mm in spawners in Iran (Renaud, 1982). Ammocoetes feed on detritus and diatoms.

Reproduction

Ginzburg (1969; 1970) examined the reproduction of this species below the Volgograd Dam on the Volga River and similar conditions may obtain in Iran. The dam has probably increased fecundity by reducing the length of the spawning migration so that the fish have more energy reserves for egg production. A spawning migration exists from December to May with a peak concentration in the second 10 days of February although the catches declined in April at least in part because of the opening of the spillway of the dam. Before the dam was built the migration from the Caspian Sea passed through the delta from mid-October to mid-December, with a peak in December. The fish migrated when water temperatures reached 10-11C and moved through channels where the current was strongest. Spawning begins at 15-16C, usually in early June but sometimes at the end of March through to the beginning of July, and temperatures during spawning are usually 15-23C. Each female produces up to 60,000 turquoise or blue-green eggs and spawns once in her lifetime. Eggs are ovate and diameter reaches 1.5 mm. The eggs are laid on coarse to fine-grained, turquoise sand at a water depth of 3.5-19.0 m, sometimes shallower. The egg colour is cryptic against the sand substrate. Many eggs are carried downstream by the current. A redd is excavated in sand or gravel by the male or by the female (authors differ on this point) and the lamprey attaches to stones by their suctorial disc. The male attaches to the female's head with his disc and wraps his body around hers. The tails of both fish quiver and eggs and sperm are released at the same time. Females release all their eggs but males may spawn again with other females. Ammocoetes hatch after 8-10 days at 17-23C. Metamorphosis of ammocoetes occurs at 8.0-11.0 cm in October in Iran.

Nazari and Abdoli (2010) examined migration and reproduction in lampreys from the Shirud in the southern Caspian Sea from 16 March to 2 May at 11.0-21.25C. The most intensive migration was at night (peaking at 2100 and declining to 0300 hours) at 16C (34.4% of the run). About 75% of the run had  passed by the time water temperature reached 16-17C. Migration stopped when temperature reached 21C. Numbers observed each night varied from 1 to 60, average 17, with peak migrations at 26 March to 10 April and 15 April to 25 April. Sex ratio was 1.07:1 in favour of males but not significantly different. Absolute fecundity was 31,758-51,198 eggs (mean 41,924 eggs) relative fecundity was 80.3-148.1 eggs/mm length (mean 107.2 eggs/mm length) and 260.8-677.4 eggs/g (mean 397.6 eggs/g). Egg diameter was 0.78-1.15 mm (mean 0.92 mm). The gonadosomatic index of females was 5.83-31.44 (mean 11.22), the peak being in mid-April. Downstream migrating lampreys were spent but no dead ones were noted so some may survive to spawn a second time. Two ammocoetes, 20 and 22 mm long, were found near the mouth of the Shirud River on 18 April 2006 (river bank in a substrate of the sand-mud, water depth <30 cm). They probably belong to the autumn migratory group (Hassan Nazari, pers. comm., 28 July2011).

Ahmadi et al. (2011, 2011) also examined fish from the Shirud and found both fall and spring migrants ready for spawning with no differences in weight, length, absolute fecundity (17,778 eggs in spring, 20,247 in fall - see above study), egg diameter (800 μm in spring, 710μm in fall) and sex ratio (close to 1:1). The gonadosomatic and hepatosomatic indices were higher in fall females. Fall migratory fish had a lower condition factor.

Parasites and predators

See above under Food. Nazari et al. (2010) also record Corynosoma in their fish. Caspian lampreys are eaten by Silurus glanis, Lota lota, Sander lucioperca, and Huso huso.

Economic importance

This species was consumed and used for oil extraction in the former U.S.S.R. (Thomas, 1961; Ginzburg, 1969). Their fat content is so high that they were once dried and used as candles (Kottelat and Freyhof, 2007) and the high fat level makes them tasty (Askerov et al., 2001). The catch in the Volga-Caspian region was 3,420,000 kg or 33.4 million fish in 1913 but fishing by state organizations ceased after the Volgograd reservoir was constructed. The mean annual catch in Azerbaijan for 1930-1963 ranged from 10 to 269 tonnes. Local fisheries continue but are of little significance. It is not commercially important in Iran for religious reasons but catches of several hundred kilograms can be made in an hour in such rivers as the Gorgan, Babol and Sardab (Ghasempouri, 1993).

This lamprey is ingested medicinally for treatment of haemorrhoids and besmi (sic, ?) by Turkmen of the southeastern Caspian (Hassan Nazari, pers. comm, 29 July 2011).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food, in textbooks and because it is reputedly ichthyosarcotoxic. Intoxication results from eating the flesh, skin or surface mucus of raw or cooked Caspian lamprey, the location of the toxin being uncertain. A biogenic amine is believed to be responsible. Mucus may cause skin irritations. Poisoning can be avoided by soaking the lamprey in brine as cooking alone is insufficient. Symptoms develop in a few hours and include nausea, vomiting, dysenteric diarrhoea, urge to urinate or defecate without ability to do so, abdominal pain and weakness. Recovery takes several days and treatment is symptomatic (Coad, 1979b). However lampreys lack scales and are not eaten in Iran.

Conservation

The Caspian lamprey has been proposed for inclusion in the "Red Book of the U.S.S.R." which forms the basis for measures to protect species (Pavlov et al., 1985) and is listed as "vulnerable" in Europe by Lelek (1987) and Maitland (1991). It is vulnerable because it migrates into rivers which are polluted and dammed and because of its restricted and declining distribution. These conditions apply particularly in Iran, although there is some evidence for spawning based on captures in the 1990s (Holčk and Olh, 1992).

Kiabi et al. (1999) consider this species to be near threatened in the south Caspian Sea basin according to IUCN criteria. Criteria include medium numbers, habitat destruction, widespread range (75% of water bodies), absent in other water bodies in Iran, and absent outside the Caspian Sea basin. Mostafavi (2007) lists it as near threatened in the Talar River, Mazandaran.

Further work

The question of adult diet remains unresolved and the general biology of this species in Iran needs to be elucidated.

Sources

The main source of information on this species is the summary by Holčk (1986) which should be consulted for further details on morphology and biology.

Iranian material: CMNFI 1970-0511, 7 ammocoetes, ? 30-82 mm total length, Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1970-0514, 33 ammocoetes, ? mm total length, Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1970-0515, 18 ammocoetes, ? 25-98 mm total length, Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1970-0534, 30 ammocoetes, ? mm total length, Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1970-0535, 14 ammocoetes, ? mm total length, Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1970-0545, 1 adult? see photo?, ?mm total length, Gilan, Safid River (3701'N, 4938'E); CMNFI 1970-0546, 2 adults, 352.0-355.0 mm total length, Gilan, Safid River (no other locality data); CMNFI 1970-0547,6 adults and 2 ammocoetes, ? photos? mm total length, Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1970-0585, 3 adults, 406.0-455.0 mm total length, Gilan, Nahang Roga River (3728'N, 4928'E); CMNFI 1971-0327A, 1 adult (part of trunk), Gilan, Shafa River estuary (3735'N, 4909'E); CMNFI 1979-0787, 11 adults, ?mm total length, Gilan, Nahang Roga River (3728'N, 4928'E); CMNFI 1980-0118,8 adults, ? mm total length, Gilan, Gelroudkhan River, tributary of the Anzali Mordab (no other locality data); CMNFI 1980-0119, 10 adults, ? mm total length, Gilan, Gelroudkhan River, tributary of the Anzali Mordab (no other locality data); CMNFI 1980-0139, 44 ammocoetes, ? mm total length, Gilan, Golshan River estuary (3726'N, 4940'E).

Acipenseridae
 

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The family is found in Europe, northern Asia and North America with 4 genera and 26 species (Eschmeyer and Fong, 2011). The Caspian Sea basin contains 2 genera and 6 native species, with both genera and 5 species recorded from Iran. The Caspian population of sturgeons is the largest in the world (Levin, 1997) and Iran is the world's second largest producer of this resource after the former U.S.S.R. (Josupeit, 1994).

These very large fishes are characterised by 5 longitudinal rows of well-developed, bony plates along the body. There is a dorsal row, a lateral row on each side and a ventro-lateral row on each side. In young fish these plates are sharp and obvious but they become smoother with age and may disappear completely. The unpaired fins have fulcra, or flat bony plates, distinct from the scutes, in front of them. Small plates, grains and denticles cover the remainder of the body and the head is covered by large bony plates. Sturgeons have an elongate snout, an inferior protrusible mouth without teeth in adults, fleshy lips and 4 barbels in a row in front of the mouth (see Keys). The vertebral column turns upward at the end into the upper lobe of the tail (known as a heterocercal tail). The first pectoral ray is a strong spine. There are few gill rakers under a single large gill cover. The skeleton is cartilaginous, there is a spiral intestinal valve, 1 branchiostegal ray, fin rays number more than the underlying basal bones which support them, no gular bones on the lower head surface and a large swimbladder. The karyotype may be complex with a very large number of chromosomes, including the very small microchromosomes, and tetraploidy, e.g. Huso huso, Acipenser nudiventris and A. stellatus have 2n about 120 while A. gueldenstaedtii has 2n about 240 and is a tetraploid. Karyotypes of 120 chromosome species are very similar indicating a slow evolution, correlated with a slow rate of DNA and protein evolution. Hybridization is common, even between genera, and hybrids are fertile and used in aquaculture in Russia (Birstein, 1993). Artyukhin (1995) gives a phylogenetic tree of Acipenser and Huso. Krieger et al. (2008) reviewed the molecular phylogeny of the order Acipenseriformes and found Huso not to be monophyletic, among other unusual placements. They conclude that some revision of classification may be needed. Rastorguev et al. (2008) examined mtDNA for Ponto-Caspian sturgeons, although sample sizes were small, and determined various relationships; Huso was basal with Atlantic species and all species in the gueldenstaedtii complex were closely related.

A general overview of sturgeon systematics and biology is given by Williot et al. (1991) and Billard (2002). Artyukhin (2006) and Peng et al. (2007) summarise the relationships aned biogeography of major clades for the order (Acipenseriformes) which dates back 200 MYA to at least the early Jurassic. A bibliography of sturgeons can be found at www.geocities.com/CapeCanaveral/Hall/1345/sturgbibl.html.

Sturgeons are subject to overexploitation, a problem addressed by Lukyanenko (1992), Vadrot (1990), Bemis and Findeis (1994), Faber (1994), Moghim (1994), Anonymous (1995), Asadollahi (1995), Ivanov et al. (1995; 1995, 1999), Vlasenko (1995), Waldman (1995), Birstein (1996), Emadi (1996a; 1996b), DeSalle and Birstein (1996), Hosseinie (1996), Khodorevskaya et al. (1997), Matthews (1998), Khodorevskaya and Krasikov (1999), G. Strieker (in CNN.com, downloaded 9 March 2002), Speer et al. (2000), Raymakers (2002), Oliver (2003), Harrison (2005), Pourkazemi (2006b), Karayev (2006), Raymakers (2006), and numerous newspaper and magazine articles. The problems for sturgeon survival in the Caspian Sea and other waters have been the subject of numerous popular and scientific articles which cannot all be cited here. A summary of the problems and management recommendations are found in De Meulenaer and Raymakers (1996) and The Sturgeon Quarterly published in New York gives recent information. Caspian populations are Endangered (high risk of extinction in the near future - Acipenser gueldenstaedtii, A. nudiventris, Huso huso) or Vulnerable (high risk of extinction in the medium term future - A. stellatus, A. persicus) (De Meulenaer and Raymakers, 1996). In 1997, the Secretariat of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) recommended a proposal to list all sturgeons as a species requiring protection because of overfishing and pollution. This would result in the close regulation of the caviar trade and perhaps a trade ban on beluga caviar. Sales of caviar in airport duty-free shops could end as passengers in a hurry would not be able to obtain the necessary CITES export permits or certificates from national authorities. After 1 April 1998 shipped caviar requires export permits or re-export certificates (Traffic North America, 1(3):14, 1998). In the year 2000, western countries through CITES (Convention on International Trade in Endangered Species) gave Iran, Russia, Kazakhstan, Azerbaijan and Turkmenistan until 31 December to impose quotas on their exports in an effort to save the sturgeon stocks. Failure to comply would result in a ban on caviar sales in the west in the year 2002 (IRNA, 25 June 2001). Australia had already banned caviar while the U.K. banned the import of caviar over 250 g without a permit (IRNA, 26 July 2000; The Times, 1 August 2000). Fishing for sturgeon was halted after the spring 2001 season in all Caspian states except Iran which has a well-managed fishery. Fishing quotas will be established after a survey in the summer of 2001 so as to avoid a complete ban on exports (Ottawa Citizen, 19 June 2001, 22 June 2001). By 2004, as Profitt (2004) points out, the agreement had not been fully implemented. Pourkazemi (2006) considers most sturgeon species in the Caspian Sea will be extinct in the near future.

Stone (2002), Stone and Mervis (2002) and Pearce (2003) give details of a dispute between scientists and CITES which arose when fishing for beluga was allowed in 2002. CITES endorsed Russian figures that showed beluga numbers increased from 7.6 million in 1998, to 9.3 million in 2001 and to 11.6 million in 2002. Scientific critics felt that there may well be less than half a million beluga, the differences being based on estimates on how many fish escape experimental trawling in relation to fish actually caught. The United States banned beluga caviar imports on 30 September 2005 and Russia advocated a moratorium on fishing of the major species (Pala, 2005). In April 2006 a global suspension of trade in caviar and sturgeon products by CITES from the Caspian Sea was extended indefinitely, with only one species allowed, the Persian sturgeon from Iran, Iran being the only country that submitted harvest data for assessment of a sustainable fishery (New York Times (www.nytimes.com), 12 April 2006, downloaded 13 April 2006). The export quota for Iran was set at 100,000 pounds of caviar. Bemis and Findeis (1994) recommend gourmets restrict their purchases of caviar to that from fish farms in order to preserve wild stocks of sturgeons.

There was a two-thirds to three-quarters decline in sturgeon numbers in the Caspian from 1990 to 1995, a result of overfishing and poaching. References cited above, The Sturgeon Quarterly (5(1/2):15, 1997) and various newspaper and popular articles reports (e.g. Boston Globe, 8 June 1997 at www.nd.edu/~astrouni/zhiwriter/97/97060808.htm and New York Times, 23 December 1995 at www.nd.edu/~astrouni/zhiwriter/spool/95122301.htm; Tidwell (2001a)) give details about poaching in former U.S.S.R. waters of the Caspian Sea. In 1996, caviar should have sold for 470/kg in Germany but was available for 100/kg illegally (Nuttall, 1996). Caviar imports to the U.S.A. increased by 100% from 1991 to 1996 (DeSalle and Birstein, 1996). The international market demand for caviar was 450 t in 1995 but the legal production from the Caspian Sea was only 228 t; the deficit being made up in part by poaching (Birstein, 1996). Russia officially exported $25 million worth of caviar in 1999 but smuggling of poached caviar was valued at $250 million (Speer et al., 2000). As a result, natural reproduction in the Volga River, the principal spawning ground in the Caspian Sea has been completely destroyed (Birstein, 1996). Bickham (1996) states that it is highly likely that the native sturgeon stocks of the Kura River are extinct or nearly so and Khodorevskaya et al. (1997) simply record that sturgeons no longer use the Kura and Terek rivers. Water pollution was given as the cause for a fall in catch in Iran from 34 tons in 2000 to 9.2 tons in 2004 (Iran Daily, 27 August 2005). Legally traded caviar fell by almost 70% between 1998 and 2003 but illegal sales probably offset this decline (www.canada.com, downloaded 16 December 2005). The export of Iranian sturgeon was expected to drop 20-25% in the year ending in March 2006 (Iran Daily, 25 December 2005). However caviar exports in the 2005-2006 year were given as 18 tons in a later report, still a drastic fall (Iran Daily, 1 May 2006). The caviar export quota for Iran in 2006 stood at 44.3 tons (Iran Daily, 11 September 2006).

Azerbaijan increased the allowable catch from 4 tonnes to 30 tonnes after independence and generally illegal catches made up 90% of all sturgeon caught (Anonymous, 1996a). The yearly allowable catch for Iranian sturgeon in 1996 was 1500 tonnes but the total catch for the Caspian Sea probably exceeds 40,000 tonnes when all countries are taken into account (Emadi, 1996b). Reduction in stocks was noted in assessments carried out in Iranian waters from 1988 onward and the it was decided to reduce the annual catch in 1996 (Iranian Fisheries Research and Training Organization Newsletter, 14:3, 1996). Iran was auhorised to take 90 tonnes of caviar for export in 2000 but the government reduced this to 70 t as a conservation measure (Speer et al., 2000). A restocking programme in Iranian waters cost about U.S.$33 million and a buyout of 4000 fixed gillnetters cost U.S.$10 million (Bartley and Rana, 1998b). Gill nets were trapping young sturgeon, Salmo caspius, Barbus sensu lato spp., Rutilus spp., and Abramis brama.

Sturgeon fingerling production was 9,124,000 in 1995 and 22 million in 1996-1997 according to the above authors, 25 million according to IRNA (2 February 1999), and 12 million according to Abdolhay and Tahori (1999). However pollution causes losses of 40-50 million fingerlings from a production of 108 million, figures at variance with the preceding (Tehran Times, 5 September 1999). The Iranian Fisheries Company produced 88.1% A. persicus in 1996, 5.4% A. gueldenstaedtii, 2.7% Huso huso, 2.5% A.stellatus and 1.3% A. nudiventris (Abdolhay and Tahori, 1999). Keyvanfar and Khanipour (1999) advocate use of trammel nets to catch broodstock for aquaculture as fish are less stressed. TACIS (2002) and Raymakers (2002) give the following table for sturgeon fingerling releases in Iran (in millions):-
 
Species/Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
A. persicus 4.06 5.92 2.93 3.57 4.66 8.05 11.02 18.75 22.59 17.30
A. gueldenstaedtii - 0.04 - - 0.30 0.52 0.67 0.92 0.42 0.96
A. stellatus 0.36 0.47 0.07 0.30 0.46 0.27 0.22 0.29 0.18 0.13
H. huso 0.14 0.17 0.45 0.30 0.49 0.29 0.34 1.44 0.69 0.41
Total 4.56 6.60 3.45 4.17 5.91 9.13 12.35 21.63 24.56 19.10

Salehi (2011a) gives a recent summary of fingerling production (and also costs of production):-

Species/Year 2000 2001 2002 2003 2004 Yearly Average %
A. persicus 13,711,199 16,278,595 12,331,354 18,420,205 17,398,000 15,177,803 78.7
A. gueldenstaedtii 1,327,480 447,855 1,564,273 - 610,000 1,197,307 4.2
A. nudiventris 1,113,826 1,782,914 1,178,582 1,414,247 1,300,000 1,532,668 7.5
A. stellatus 226,373 820,136 1,182,902 196,082 322,000 635,893 3
H. huso 1,900,919 640,963 2,372,794 42,075 1,570,000 1,246,938 6.6

 Abdolhay and Tahori (2006) give descriptions of hatcheries in Iran and the process of fingerling production, including transportation and incubation techniques, pond and tank culture, release strategies, and strategic development plans. Trial production of larvae first occurred in 1922, reaching about 2 million in 1928 but hatchery production first began in 1971. Sturgeon fingerling production was low between 1981 and 1986 as the focus shifted to Chinese carps and Rutilus frisii. Brood stock are captured in rivers by beach seines or selected from fishery stations in February-March. The fish are checked by sampling eggs and  examining germinal vesicle development. Only suitable fish are injected with ovulation-inducing hormones in March-May over 3-5 days. The fish are killed and the collected eggs are fertilised with diluted sperm (1:200 with hatchery water) to avoid polyspermy as eggs have many micropyles. Eggs are incubated in jars or troughs for 5-10 days and newly emerged larvae are held in circular tanks. Fry are raised in fertilised ponds for 40-60 days until they reach 3-5 g. Fingerlings are released in river deltas in June-July. Release strategies are spot planting of all fish at once, scatter planting at several sites in the same region and trickle planting over a period of time. Fish are captured as adults 10-20 years later at a return rate of 1-3%.

Fingerling production in 1000s was:-

Year/Species

H. huso A. nudiventris A. gueldenstaedtii A. persicus A. stellatus Total
1993 301 no data no data 3570 300 4171
1994 491 no data 300 4662 456 5910
1995 286 no data 522 8049 268 9125
1996 344 102 673 11,018 316 12,455
1997 1437 230 919 18,751 288 21,627
1998 687 678 418 22,586 181 24,552
1999 406 304 722 17,300 132 18,864
2000 1901 114 1327 13,711 226 17,279
2001 641 1782 447 16,278 820 19,970
2002 2404 1819 1816 12,301 1300 19,642
2003 42 1414 0 18,388 196 20,041
2004 1464 1311 617 17,412 314 21,121
Total 11,175 7757 7805 191,682 9774 258,567

Iranian sturgeons and their caviar increased in importance in the 1990s as the Russian caviar trade was taken over by a black market system with poor attention to quality. However caviar production in Iran fell in the 1990s through poaching and oil pollution in other parts of the Caspian Sea. Production was 130 tonnes per year, down from 160 tonnes up to 1989 (IRNA, 31 August 1998; Tehran Times, 13 December 1998). Caviar comprises 50% of the seafood exports from Iran (IRNA, 21 October 1998) and formed 1.2% of Iran's total exports for the first four months of the Iranian year in 1998 (in 1994 it was 62% (Salehi, 1999)). On the 23 October 1998, the Islamic Republic News Agency (IRNA) reported that Iran had stopped exporting caviar to protect the resource, this despite the number of sturgeons in the sea having risen from 6 to 22 million over the past couple of years. The same article reports 22 million sturgeon fingerlings stocked in the Caspian Sea by Iran. The export of 111 tons of caviar in 1998-1999 was worth $29.5 million; catches had been reduced to save the species from extinction (Tehran Times, 1999). The export amount was over 80 tonnes since the beginning of the Iranian year (21 March 1999), a 30% drop in production over the previous year (IRNA, 26 January 2000). The 1999 total export was 90 tonnes of caviar worth 70 million deutschmarks, a monetary increase of 42% (IRNA, 4 May 2000). The 2000 export of caviar was 70 tonnes (or 71.5 t, or 80-90 t, reports vary) worth 100 million deutschmarks (or $34.4 million) with 80% going to Europe, 10% to Japan and the rest to various other countries; in addition 100-200 tonnes of sturgeon meat worth $2-3 million is exported annually (IRNA, 14 July 2001, 7 August 2001, 30 September 2001). The sturgeon catch was 75 t in 2002 with 50 t being exported for U.S$30 million (IRNA, 11 June 2003). Golestan Province produced 43% of Iranian caviar, a 17.5% increase presumably in 2000 over the 1999 catch. There are 295 fishermen using 91 fishing boats (IFRO Newsletter, 29:4, 2001).

Sturgeon stocks were evaluated in Iranian waters in 2000 (M. Moghime and F. Parafkandeh Haghighi, 5th International Symposium on Sturgeon, Iranian Fisheries Research Organization, 9-13 May 2005, Ramsar; Haghighi, 2006; Moghime, 2006). The catch was 855 t yielding 92.5 t of caviar, with Acipenser persicus comprising 472 t, A. stellatus 201 t, H. huso 105 t, A. gueldenstaedtii 48 t and A. nudiventris 31.8 t. The catch-per-unit-effort was A. gueldenstaedtii (0.285 kg), A. persicus (2.296 kg), A. nudiventris (0.089 kg), and A. stellatus (2.941 kg). Mature females comprised A. gueldenstaedtii (80.0%), A. persicus (71.8%), A. nudiventris (51.3%), A. stellatus (74.7%) and H. huso (67.4%). The gonadosomatic value in terms of body weight was A. gueldenstaedtii (9%), A. persicus (11%), A. nudiventris (8%), A. stellatus (14%) and H. huso (2.8%). The catch in Gilan and Golestan provinces was A. stellatus (11%) and H. huso (35%) of the total catch. In Gilan, the catch was made up of A. gueldenstaedtii (44.3%), A. persicus (16.4%) and A. nudiventris (3.8%) and in Golestan these values were 16%, 72% and 0.9% respectively. The average age in Gilan and Golestan respectively was A. gueldenstaedtii (15.5 and 18.5 years), A. persicus (20 and 19.2 years), A. nudiventris (15 and 19.3 years), A. stellatus (13.8 and 13.2 years and H. huso (15.8 and 18 years).

Tavakoli et al. (2007)and Kor et al. (2008) surveyed stocks in the southern (2004-2005) and northern (2006)  Caspian Sea respectively. In the southern Caspian Sea catch of 288 fish total, catch per unit effort was 2 fish in summer and 1.38 fish in winter. The most abundant species was Acipenser persicus with 1.67 fish per trawl in summer (142 fish) and 0.88 in winter (75 fish). A. stellatus was 0.22 and 0.48 fish. No Huso huso were caught in winter and only 4 fish in summer. A. nudiventris comprised only 4 fish too and and A. gueldenstaedtii 3 fish, both in total. Kor et al. (2007) examined the population structure of sturgeons in the coastal waters of Mazandaran, less than 10 m deep, for 2003-2005. The number of fish captured in 2003-2004 was 301 with catch per unit effort (CPUE) being A. persicus 4.07, A. stellatus 0.58, A. nudiventris 0.22, and A. gueldenstaedtii 0.15, and in 2004-2005 the catch was 412 fish with CPUE A. persicus 6.15, A. stellatus 0.23, A. nudiventris 0.12, A. gueldenstaedtii 0.35, and Huso huso 0.02.

The world's leading importer of caviar, Caviar House, with an annual turnover of $100 million took 85% of its caviar from Iran (Lindberg, 1994; Pala, 1994). The value of the caviar fishery in Iran was estimated at U.S.$45 million (Bartley and Rana, 1998a; 1998b) and is the main fish product exported with an international cultural and culinary significance. The caviar industry in Iran is a state monopoly under strict control and has not suffered from poaching to the same extent as happened in the former U.S.S.R. after the collapse of central authorities. There has been some smuggling reported via Bandar Abbas to Ras al Khaimah across the Gulf and re-labelling of Azerbaijani caviar as Iranian to fill Iranian contracts with the U.A.E. An illegal trade in "bazaar" caviar reached a peak of 70 tonnes in 1983, about 50% of the legal exports (Taylor, 1997). This caviar was processed poorly in primitive tins with sealant rings made from old tyres; consequently the price for this product was low. The Iranian government actively sought to suppress this trade and after 10 years of effort reduced smuggling to 2-4 t annually, a level similar to that prior to 1979. In 2003 however, 3.8 t of smuggled sturgeon fish and caviar were reported as confiscated for the previous year (ending 20 March) in Mazandaran (IRNA, 21 April 2003). Evidence of Iranian control of the industry is seen in the 1994 setting of a minimum catch size limit of 1 m on all sturgeon species and limiting fishing sites along the Caspian coast to 90 (Josupeit, 1994; De Meulenaer and Raymakers, 1996). Additionally Iran now stocks more sturgeons from farms than it catches (The Times, London, 8 July 1998). However the BBC News (6 May 1998) reports declines in catches of sturgeon over the past 5-10 years.

The illegal market in caviar has been estimated at 500 million with some caviar fetching up to 20,000 a kilogramme (The Times, 28 December 2006). In Britain, caviar tins must indicate their exact source and without this label will be seized by Customs. The label will carry a species code, source of the caviar, country code, year of harvest, processing plant registration number and lot identification number, all in an attempt to regulate and eliminate sales of smuggled caviar. Much of the smuggled caviar is sold under the counter or to those who have pre-ordered it, or by shops that then state they were unaware of its illegal status.

Although caviar is the main market item for sturgeons, Iran is investigating the use of fillets and smoked and salted A. stellatus in vacuum packs for export (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 45-46, 1997). Smoked, marinated and canned sturgeon, smoked sturgeon in vegetable oil and frozen fillets are now available (2001) from several Iranian companies. Javanmard and Taghavi (2002) investigated the microbiological and chemical characteristics of these products and only one had a total coliform count more than the European Community standard. Gelatin has also been produced from sturgeon fish skin on an experimental basis (Iranian Fisheries Research Organiztion Newsletter, 30-31:6, 2002; Koochakian Sabour et al., 2001).

All sturgeon species in the Caspian Sea basin are listed as "endangered" or "vulnerable" and are maintained in part by hatchery stocks (http://www.sturgeons.com/htdocs/status.html). Survival and growth of sturgeon fry in the Caspian Sea is reviewed in Farsi by Aslaanparviz (1992).

The countries of the Caspian littoral are attempting to conserve their sturgeon stocks. Even the Swiss company Caviar House has established a hatchery in Iran to increase stocks (Anonymous, 2001a). An agreement for the "Preservation and Exploitation of Live Resources in the Caspian Sea" was made between Iran, Russia, Azerbaijan, Turkmenistan and Kazakhstan in 1996. Luk'yanernko et al. (1999) point out the need for the agreement to recognise that sturgeons are sustained by an ecosytem involving the whole Caspian Sea and the inflowing rivers, that there must be an absolute ban on uncontrolled fishing for sturgeon in the sea and that national quotas must reflect the real contribution of a a particular state to overall sturgeon stocks. Without adequate measures, these authors predict extermination within 5-7 years. Export of caviar is made a monopoly of the governments concerned in an effort to minimize smuggling of low quality caviar. Jenkins (2001) gives reasons why an international trade ban would not necessarily help conserve the sturgeons - most poached caviar is sold within Russia, for example. Sturgeon catches are restricted to rivers and their estuaries and open-sea trawling is banned. The five countries are investing $150 million in a fish farm programme to save the sturgeon from extinction: Russia will have 10 new farms and renovate 8 farms on the Volga River, and both Kazakhstan and Iran have a new farm (Abzeeyan, Tehran, 7(4):II-III, 1996; The Sturgeon Quarterly, New York, 4(4):1, 1996; newspaper reports). Russian strategies for conservation of sturgeon are reviewed in Artyukhin et al. (1999) and the status of the Russian sturgeons is given in Vaisman and Raymakers (2001). Some sturgeon species are now on Appendix 2 of the U.N. Convention on International Trade in Endangered Species of Flora and Fauna (CITES) in an effort to control the import and export of meat and caviar (Pearce, 1997). The U.S. Fish and Wildlife Service, in an attempt to combat overfishing of sturgeons, now requires valid CITES permits for imported caviar (Anonymous, 1998a). DNA tests will be used to confirm the species of sturgeon listed on the shipment and to eliminate illegal mixtures with inferior quality roe. Even cats are now used to detect smuggled sturgeon in Russia. A cat named Rusik is able to detect sturgeon hidden in trucks better than sniffer dogs (National Post, 9 July 2003, p. A12).

The number of adult fish in the Caspian Sea had declined from 142 million in 1978 to 43.5 million fish in 1994. Ivanov et al. (1999) and Khodorevskaya and Krasikov (1999) review the status of stocks in the Caspian. Marked declines are evident and only the Iranian catches are reasonably stable from 1977 to 1994. All species studied in Iranian waters had a very low percentage of fish older than 20 years, are evidently in need of protection (Iranian Fisheries Research and Training Organization Newsletter, 16:4-5, 1997). An initiative to make the sale of caviar from threatened sturgeon species illegal is being proposed by the Species Survival Commission and the IUCN (The Sturgeon Quarterly, New York, 4(4):1, 1996; Morris, 1997). Part of this initiative would involve genetic testing of the caviar as a means of identifying the species of sturgeon. Paddlefish eggs from Montana, U.S.A. costing less than $5 an ounce have been repackaged as beluga caviar in Russia and eastern Europe and sold in the U.S.A. for $50 an ounce. The U.S. Fish and Wildlife Service was to begin monitoring the caviar trade on 1 April 1998 using DNA tests (U.S.A. Today, 18 November 1997, internet edition). Birstein et al. (1998) describe a molecular technique for identifying the species source of commercial caviar (see also Brainard (1998)). They found 23% of species designations by caviar suppliers to be incorrect, indicating possible illegal harvesting and poaching. The Iranian Fisheries Research and Training Organization Newsletter (20:4, 1998) also reports on nuclear DNA amplification and a marker which distinguishes species. Additional research is being carried out on egg identification using ultrastructural characteristics (L. Debus and M. Winkler, 1998, www.uni-rostock.de).

Sturgeons have been fished since the Neolithic, perhaps 6000 or more years ago (Tsepkin, 1986) but only in recent years have the stocks declined significantly. Historical records show it was possible to catch 500 Huso huso weighing 600-1000 kg in about 2 hours in the Volga delta at the end of the eighteenth century (Birstein, 1993). All the sturgeon species were bigger on average and lived longer than now based on archaeological excavations (Tsepkin and Sokolov, 1971). The sturgeon catch in the Caspian Sea declined from 27,400 tonnes in 1977 to 8,900 tonnes in 1990 (Vlasenko, 1995). The catch in 1993 was only 4,200 tonnes because of poaching and pollution of the Volga River (The Sturgeon Quarterly, 3(1):12, 1995). An estimated 90% of the Caspian sturgeons are killed before they mature (Platt, 1995). Catches in Russian waters of the Caspian Sea declined from 7106 tonnes in 1992 to 3426 tonnes in 1993 to 2960 tonnes in 1994 but 90% of the real catch is unreported (16,700 tonnes were reported in 1983 for comparison). The number of adult sturgeons in the Caspian Sea is estimated to have declined from 142 million fish in 1978 to 43.5 million fish in 1994 (De Meulenaer and Raymakers, 1996). The Caspian Sea Sturgeon Ranching Programme of the former Soviet Union helped to sustain fisheries but declines still occurred (Secor et al., 2000).

Catches in Iran, however, increased over a five year period, perhaps because of heavier fishing pressure. Sternin and Dor (1993) cite figures for 1986-1990 of 1690 tonnes, 1759 t, 1851 t, 2051 t and 2021 t, while U.S.S.R. catches over the same period were 21,817 t, 20,991 t, 19,027 t, 16,880 t and 15,056 t. A conflicting study noted a decline from 122,000 sturgeons caught in 1986 to 68,000 in 1993 (Abzeeyan, Tehran, 6(5, 6):IV-V, 1995). De Meulenaer and Raymakers (1996) summarise Iranian catches as 700 to 2500 t in the twentieth century, peaking towards the end of the 1960s, falling to 1000-1500 t in the 1970s and increasing from 1450 t in 1982 to a 1991 high of 3036 t but falling off rapidly to 1700 t in 1994. Josupeit (1994) gives catches in Iran in tonnes from 1982 to 1992 as 1450, 1288, 1557, 1650, 1690, 1759, 1851, 2051, 2645, 3036 and 2692 t. The commercial sturgeon catch in the Safid River delta fell from 6700 tons in 1961 to less than half a ton in 1993 (http://www.oneworld.org/patp/pap_overview.html). Spawning may no longer take place in the Safid River (De Meulenaer and Raymakers, 1996). Zanusi (1995) maintains that over 40% of the total sturgeon fishing in the Caspian Sea is centred on Bandar-e Torkeman in Mazandaran, presumably including the acknowledged black market in sturgeon products. Lewis (1980) gives some information about the Iranian black market in caviar shortly after the Islamic Revolution before controls were re-established. A 400 g tin was selling in Paris black market for $40 compared to $310-315 for the best Russian beluga. Caviar production in the three Caspian coast provinces of Iran for the 1990s were as follows in kg after Nezami et al. (2000):-
 
Year/Province Gilan Mazandaran Golestan
1991 75,974 78,713 128,446
1992 81,520 80,758 99,336
1993 51,480 58,543 83,026
1994 40,368 52,162 87,576
1995 37,241 43,831 70,154
1996 41,743 41,432 79,063
1997 28,641 42,329 58,304

The problem of overexploitation of sturgeons is compounded by their long life span and their use of rivers as spawning grounds such that they are easily caught on this migration from the sea. The migration and spawning is timed differently between species and populations within species. Some sturgeons migrate long distances up rivers while others have a shorter migration. Eggs are deposited on stony or gravel bottoms and hatch after a short incubation. As an example, a study of sturgeon migrations in the Gorgan and Tajan rivers of Iran showed a movement of 2 out of 28 fish caught at one station reached the second station in the Gorgan and no tagged fish reached higher stations in the Tajan - the rest were caught by fishermen (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 53, 1997). Ramin (1998) studied migration in the Safid River over 35 days in April-May, from the mouth to 30 km upriver for A. gueldenstaedtii, A. persicus and A. stellatus. Shallow water caused by sand-clay deposits and illegal fishing did not prevent successful migration. It was recommended that the Manjil Dam be used to regulate water flow and a total ban on fishing, especially at the mouth, during the March-May spawning season be implemented.

In 1998 the comb jelly, Mnemiopsis leidyi, reached the Caspian Sea via ship ballast and newspapers speculated that the sturgeon populations would be affected, although how was not specified.

The young migrate downstream to feed and grow in the sea. Old reports have sturgeons overwintering in deeper parts of rivers, in a kind of torpor and with a viscous substance coating the body (Baird, 1873). The barbels are highly sensitive and, as soon as they detect food, the tubular mouth protrudes to suck in the prey. Food is benthic organisms although some are predators on larger fishes. Young sturgeon in Iran feed predominately on polychaetes while crustaceans are a minor food item, probably caused by lower oxygen conditions favouring the former (Haddadi Moghaddam and Negaresten, 2003). Pourgholam (1994) reports the coelenterate Polypodium hydriforme from sturgeons caught on the Babol Sar and Bandar-e Torkeman fishing grounds in Mazandaran where up to 25.6% of fishes are infected, particularly Huso huso and Acipenser gueldenstaedtii. This parasite destroys the eggs of sturgeons, affecting reproductive success and the caviar industry (see also Raikova (2002)). Incubated eggs of sturgeons are susceptible to various species of fungi, with up to 70-90% of eggs being lost (Czeczuga et al., 1995). Czeczuga et al. (1995) report 43 species of fungi on eggs of sturgeons from Russian and Iranian Caspian Sea samples immersed in water from a Polish river, lake and pond. Huso huso and Acipenser gueldenstaedtii persicus (sic) eggs carried the fewest species of fungi, about half the load of other sturgeon species. Ghoroghi (1996) reports metacercariae of Diplostomum spathaceum in the lens of 22% of fingerlings on the Shahid Beheshti Fish Farm causing weight loss and mortality. External parasites on sturgeons include Pseudotracheliastes stellatus, Nitzschia sturionis, Diclybothrium armatum, Cystoopsis acipenseris and Diplostomum spathecum with the highest prevalence in Huso huso at 60% and the lowest in Acipenser persicus at 13.9% (A. Hajumoradloo in 5th International Symposium on Sturgeon, Iranian Fisheries Research Organization, 9-13 May 2005, Ramsar). Ghaemi et al. (2006) found strains of mycobacteria in Iranian sturgeons and Mycobacterium marinum can cause fish tank granuloma, a disease in humans although none was found in fishermen.

Many sturgeons in former Soviet waters of the Caspian Sea have developed fatal diseases associated with chemicals such as phenols, waste fluids and air from gas production facilities associated with the petrochemical industry. Both the sturgeon and their caviar are now inedible. Iranian sturgeons are believed to be less affected but since sturgeons migrate they are susceptible to extra-territorial pollution (Golub, 1992).

Sturgeons are some of the most important commercial species in the world, with 90% of the total catch coming from the former U.S.S.R. and only 6% from Iran (but see later under Acipenser gueldenstaedtii where Iranian production of caviar increased in the 1990s). Over 90% of all sturgeons are caught in the Caspian Sea. The proportion of catch is heavily weighted towards the former U.S.S.R. (compared with Iran in parentheses) with figures from 1971 to 1988 as given by Sternin and Dor (1993) being 19,100 tonnes (2400 t) for 1971, 20,400 t (2200 t) for 1972, 24,958 t (1801 t) for 1978, 26,322 t (1578 t) for 1979, 26,697 t (1429 t) for 1980, 26,452 t (1496 t) for 1981, 25,704 t (1450 t) for 1982, 25,570 t (1500 t) for 1983 and 18,470 t (1700 t) for 1988. The Volga River and its delta provided 75% of the commercial sturgeon harvest in the Caspian Sea with Acipenser gueldenstaedtii making up 60-70% of this amount, A. stellatus about 30% and Huso huso 5-6% (Khodorevskaya et al., 1997). Williot and Bourguignon (1991) summarise sturgeon catches in Iran from FAO data for 1965 to 1987 as ranging from a low of 1429 t to a high of 3000 t. Abdolhay and Tahori (2006) summarise catches as follows:-

 
Year Total catch (tonnes) A. stellatus (%)  Osetra* (%) H. huso (%)
1972 1500 34.0 36.3 29.7
1991 3036 49.5 41.0 9.5
1994 1700 49.5 41.0 9.5
1997 1300 35.8 54.3 9.9
2000 1000 35.8 61.0 3.5
2001 870 28.2 69.3 2.5
2004 600 10.7 74.6 14.7

* presumably includes A. persicus and A. gueldenstaedtii

Only 5% of Iranian caviar is consumed in that country, the rest being exported. Domestic prices are very high at about U.S.$340 per kilogramme and the caviar is rationed to 100 g per person. Contraband caviar can be bought at about half this price around Bandar Anzali and at least 30 t are smuggled out of the country each year (The Daily Star, 7 December 2004, www.dailystar.com, downloaded 17 December 2004). In 1996, 95 t out of an estimated 120 t catch was exported although formerly as little as 38.7% was exported as in 1978. Iran is the chief exporter to the European Union, the weight varying from 95 to 125 t from 1988 to 1994 (De Meulenaer and Raymakers, 1996). Caviar exports by year for Iran are given by these authors as:-
 

Year

1988

1989

1990

1991

1992

tonnes

225

249

226

225

169

U.S.$1000

42,155

47,865

46,005

53,800

42,004

U.S.$/kg

187

192

204

239

249

The export volume of caviar for 1997-1998 was 105 tonnes worth 62 million German marks (= U.S.$34 million) (IRNA, 16 March 1998).

Prices outside Iran have fluctuated widely because of large amounts of illegal and often poor quality caviar flooding the world market. Caviar exports are declining in the 1990s reflecting, it is believed, the loss of sturgeon stocks in the Caspian Sea (De Meulenaer and Raymakers, 1996).

Caviar is the main product but the flesh is also eaten (a religious ruling was made in the 1980s to the effect that Iranian ichthyologists had determined sturgeons to be fish with scales - see below). Early reports of poisoning from sturgeon eggs have been attributed to poor preservation and consequent bacterial contamination (Halstead, 1967-1970). The milt of Acipenser sturio contains a toxic substance known as "sturin" and although this species does not occur in Iran a similar toxin may occur in Iranian Acipenser (Coad, 1979b).

The swimbladders of sturgeons have been converted to isinglass, a transparent gelatin used in a variety of products including as a wine and beer clarifier, in jams and jellies and in glass and pottery. Gmelin (2007) mentions that in 1770-1774 people along the Langerud were catching large numbers of sturgeons for their isinglass only, the caviar and flesh not been used. Sabour (2006) found the swimbladder in Iranian sturgeons to weigh 250-285 g in H. huso, 35-92 g in A. stellatus and 85-160 g in Acipenser spp and could be was processed to isinglass at 15-20%. Koochekian et al. (2006) found a higher percentage production of isinglass from A. persicus/A. gueldenstaedtii than in Huso huso or A. stellatus. Recently Iranian scientists have investigated production of leather from sturgeon skin (Iranian Fisheries Research and Training Organization Newsletter, 4:2, 1994; Davarzani, 1995; Iranian Fisheries Research Organization Newsletter, 22:2, 2000; Iran Daily, 17 January 2006). An estimated 1 million square feet of leather could be produced and used in handicrafts, book binding, waterproof products and ornaments.

Various methods to enhance the sturgeon fisheries have been investigated in Iran. Some are given under the Species Accounts and others are summarised here. Experiments with pen culture in Gorgan Bay have been carried out to increase production and with cross-breeding Huso huso and Acipenser stellatus to create new commercial and resistant stocks (Iranian Fisheries Research and Training Organization Annual Report, 1992-93). A Farsi review of sturgeon culture is given by Rasoli (1992). Even surgical procedures under anaesthesia have been tried to remove eggs through a 15-20 cm incision as part of attempts to increase caviar production (Mokhayer, 1993; The Times, London, 8 July 1998). Ultrasonagraphy has been used successfully to distinguish males, females and immature fish without damaging them (Vajhi, Moghim, Veshkini and Masoudifard (1999) www.mondialvert99.com, downloaded 31 May 2000; Moghime, 2006). The accuracy was 97.2% for A. stellatus and 100% for A. gueldenstaedtii, A. nudiventris and H. huso. Vacuum pumps have also been used to breed female Acipenser nudiventris and male A. stellatus. The fish are anaesthetized with xylazine hydrochloride and then eggs and sperm are pumped out, the advantage being that females can be returned alive to the sea (Iranian Fisheries Research and Training Organization Newsletter, 13:5, 1996). Bahmani et al. (2001) compared haematological parameters in Acipenser persicus and Huso huso and how these changed with age. Haemtaological indices give insight into the physiological condition and aid in the selection of broodfish. Cryopreservation of sperm has been carried out as stripping fish late in the season is difficult. Sperm in liquid nitrogen with an extender is viable for 1.5 to 2 years (M. Moghim and H. N. Moghadam in 5th International Symposium on Sturgeon, Iranian Fisheries Research Organization, 9-13 May 2005, Ramsar; Moghadam, 2006). The colour of gill nets used in the capture of sturgeons has been investigated with blue nets having a yield of 42.6%, white 29.8% and green 27.5% (5th International Symposium on Sturgeon, Iranian Fisheries Research Organization, 9-13 May 2005, Ramsar). Studies on the fingerling production of hatcheries include the nature of the phytoplankton community and the benthic biomass, parasitic infections (e.g. Diplostomum sp. on the eyes and Trichodina sp. on the gills were noted at an incidence of 25% and 35.85, productivity (6,509,185 fingerlings produced from 31 March and 28 July 2000 in two hatcheries with some transfer of Huso huso fingerlings from another hatchery), survival rates (56.7% and 25.2% for A. persicus and H. huso respectively), and growth rate and condition factor (generally low). Kami et al. (2005) studied the biology of pond turtles (Emys orbicularis) which live in culture ponds along with sturgeon. One dietary item was Acipenser persicus. The use of probiotics, microbial cells in the diet, used to improve health and thus enhance quality of farmed fish is of potential use in sturgeons as reviewed by Askarian et al. (2006). Bahmani (2006) used both histology and haematology on Acipenser persicus, A. gueldenstaedtii and Huso huso to determine physiological condition  of fish in ponds and rearing tanks, comparing the results with natural conditions (similar) and finding that fibreglass tanks were more suitable than rearing ponds. Banadani (2006) examined the environmental conditions in the Gorgan River, a major site for release of sturgeon fingerlings. Mohseni (2006) studied the effect of stocking density of eggs and larvae in incubators on their survival, growth and appearance of deformities. Increased density reduced survival and growth and increased deformities. Parandavar (2006) compared production of sturgeon from broodfish maintained on farms to those produced from fish taken from the wild. Salehi (2006) analysed the economics of sturgeon fingerling production and found labour costs were 55%, food and fertiliser 14%, maintenance 7% and fertilised eggs 5%. A single fingerling cost 992 rials to produce in Iran, varying between 447 and 1224 rials among hatcheries. Yousefian (2006) gives details of the production of fingerlings at the Shaid Rajii Fish Farm in 2002. This farm produced 2,898,086 or 93.27% of the fingerlings released into the Tajan, Larim, Goharbaran and Sardab rivers. These fingerlings had an average weight of 3.58 g and condition factors were 0.4 for Acipenser persicus, 0.37 for A. gueldenstaedtii and 0.31 for A. stellatus, in total and average grade for the condition factor. Fazlei (no date) summarised the number and quality of fingerlings released into Mazandaran and Golestan provinces. The most important rivers for release were the Gorgan (8,659,377 fingerlings, average weight 2.55 g), Tajan (1,453,410, 4.12 g), Larim (1,211,875, 3.4 g) and Goharbaran (743,561, 3.09 g). A. persicus comprised 87.7% of the fingerlings, A. gueldenstaedtii 6.6%, H. huso 3.3% and A. nudiventris 2.4%. The International Sturgeon Research Institute has developed a food formula based on Iranian sturgeon species. Previously food for aquaculture came from Europe and the domestic version was demonstrated to be superior (Iranian Fisheries Research Organization Newsletter, 58 & 59:2, 2009). The hybrid sturgeon known as bester (female beluga x male sterlet) has been investigated  for expanding sturgeon culture in Iran. Growth was significantly better than in beluga (Iranian Fisheries Research Organization Newsletter, 58 & 59:4, 2009). Jafarian et al. (2009) studied the use of probiotic bacilli to encapsulate Artemia urmiana nauplii and the yeast Saccharomyces cerevisiae used to encapsulate Daphnia magna, Artemia and Daphnia being used as live food for sturgeon larvae. Both treatments increased growth parameters and feeding efficiency in A. persicus, A. nudiventris and H. huso.

Lake Orumiyeh has been used as a source for Artemia urmiana or brine shrimp to be used as a live food in sturgeon aquaculture (Azari Takami, 1987; 1993). Brine shrimp were found to be a better food than white worms or Daphnia, being cheaper and easier to prepare, easier to store as cysts, sturgeon fry showed better growth, pathogens were less, mortality was lower and yield higher. Since 1972 almost 50% of fry diet has been brine shrimp. The large mouths of sturgeon fry enable them to take brine shrimp nauplii and even adults a few days after yolk-sac absorption. Fry are grown to 100-120 mg within 7-10 days and then released into the sea.

Anonymous (1961b) reported on the caviar industry in Iran which at that time was about 5-6% of the world supply. The Food and Agriculture Organization of the United Nations in their Yearbook of Fishery Statistics reported catches of sturgeons from 1980 to 1985 as 1429, 1496, 1450, 1288, 1557 and 1650 tonnes respectively. Soviet catches of sturgeons in all waters, not just the Caspian Sea, ranged from 22,772 to 26,697 tonnes for the same period. Petr (1987) summarised FAO statistics for Iran and gave mean landings of sturgeons as 2300 tonnes (1964-1970), 1800 t (1971-1975), 1500 t (1976-1980), and 1774 t (1980-1985) but some of this data is very approximate being repeats of a 1500 t value as an estimate (see also above for more figures). A pamphlet from the Ministry of Jahad-e Sazandegi (= Construction Crusade or Rural Development), which is charged with fisheries in Iran, gave catches for "caviar fish" of 3036 tons (presumably tonnes) in 1991 and 2692 tons in 1992. The catch in 1995 was 995 tonnes yielding 134 tonnes of caviar with 74% of the catch from Mazandaran province (http://netiran.com:80/news/TehranTimes/html/95122503TTEC.html). Other news reports give the 1995 catch as 142 tonnes of caviar, in 1996 112 t and an estimated 140 t in 1997. The 200 t of caviar produced in 1992 was worth $100 million through export while the 1997 catch was worth only $60 million despite a 50% increase in price. The Tehran Times (30 May 1998) reported that caviar production was reduced from 220 tonnes to 40 tonnes during the previous 6 years to preserve stocks. The allowable catch in 2003 was set at 676.4 t for Iran, a decrease from 685 t in 2002, with caviar exports set at 78.8 t. Figures for other Caspian states were Azerbaijan 130 t (9.1 t of caviar), Russia 429 t (30.3 t), Kazakhstan 216 t (23.18 t), and Turkmenistan 56.25 t (5.85 t)(IRNA, 28 December 2002).

Caviar from Iran commanded a higher price than that from the former U.S.S.R. in the 1990s (Christie, 1995). Catches in the 1952-1957 period yielded an annual average yield of 120 tons (sic, possibly tonnes here and below) of caviar (Kayhan International, 1 December 1962) which agrees closely with the figure given by Job (1961a) of 90-115 tons (sic) annually. Catches from 1965/66 to 1968/69 in Iran rendered 208 to 219 tonnes of caviar annually from 1996 to 2290 tonnes of the three main species fished (A. gueldenstaedtii (presumably including A. persicus), A. stellatus and Huso huso)(Andersskog, 1970). The catch in 1961-1962 was 170 tons (or 178 tons, V. D. Vladykov, in litt., 1966; differing data is not unusual as effectiveness of information gathering varies) and this was the first season when exports to the U.S.A. exceeded that to the former U.S.S.R., 56 to 46 tons, with 58 tons going to Europe and about 10 tons consumed locally. The caviar yield in 1956-1957 was low, at 134 tons (or 137 tons, V. D. Vladykov, in litt., 1966) and averaged 120 tons from 1952-1957 (Kayhan International, 1 December 1962), a decline over levels prior to dissolution of the Iran-Soviet company. White (1988) reported a caviar export of 150 tonnes from Iran with a value of U.S.$20 million out of a 250 tonnes annual production. Caviar yield in airtight containers was 233 tonnes (1981), 204 t (1982), 222 t (1983), 247 t (1984), 304 t (1985), 283 t (1986), 296 t (1987), 281 t (1988), 286 t (1989), and 290 t (1990) (Sternin and Dor, 1993). Production of caviar in the 1990's dropped steadily from 160 tonnes to 120 tonnes as the Caspian became more polluted (Tehran Times, 5 August 1999) and the catch for the year ending in March 2000 was expected to be less than 100 tonnes (Reuters News Service, downloaded 1 September 1999). Pollutants from Russia, Azerbaijan and Kazakhstan include oil spillage from old equipment at offshore sites and 12 million cubic metres of sewage from the Volga. The sewage includes toxic PCBs, phenol, heavy metals, dioxins and DDT as well as household, agricultural and industrial wastes. A 10-year ban on sturgeon fishing would have to be placed into effect to allow stocked sturgeon to mature and breed. Research on qara burun (A. persicus) and uzun burun (A. stellatus) in Iran has shown heavy metal (cadmium, copper, zinc, lead and mercury) density in caviar and flesh to be 10 times less than the global safety standard (IRNA, 15 January 2002; IFRO Newsletter, 28:2, 2001). Pourang et al. (2005) examined all five sturgeon species in Iranian waters and found all toxic trace elements (Cd, Cu, Pb and Zn) to be markedly below international guidelines for human consumption. Kajiwara et al. (2003) demonstrated contamination by organochlorines in Iranian sturgeons. DDT and its metabolites predominated at 180-18,000 ng/g on lipid weight followed by PCBs at 110-1900 ng/g. Generally Huso huso was the most contaminated species and contaminant concentrations were higher in Azerbaijan and Kazakhstan than Iran, the latter having fewer oil wells. Gelodar (2006) evaluated four caviar processing plants for their hygienic standards using the Hazard Analysis and Critical Control Point (HACCP), an internationally recognized food safety system. Those plants following the European Community code had decreased their contamination levels.

70% of Iranian caviar is produced in Mazandaran, 130 tonnes in 1994 (Abzeeyan, Tehran, 6(5, 6):III, 1995) although this conflicts with a report from IRNA for 2 May 1998 where Mazandaran has 35% of the total Iranian output at 44 tonnes for 1997-1998. 95% of the Mazandaran caviar is exported along with 60 of 260 tonnes of sturgeon meat (IRNA, 2 May 1998). The Bandar-e Torkman fisheries organization in Golestan Province (eastern Caspian Sea) planned to process 360 tonnes of sturgeon and 48 tonnes of caviar in 1999-2000 (IRNA, 14 December 1999). Newspaper reports in 1995 gave a value of U.S.$40 million for caviar exports from Iran; another report gave U.S.$50 million for 250 t (Food and Agriculture Organization, Fisheries Department, 1996). This is less than the value of half a day's oil sales but the caviar fishery is a national symbol (Christie, 1995). Mazandaran produced 17 tons of caviar in 10 months in 2003-2004 as well as 140 tons of meat (www.iranmania.com, downloaded 4 October 2004). In the Iranian fiscal year ending 20 March 1998 Iran exported 105 tonnes of caviar worth about U.S.$11 million (Anonymous, 1998b). The 2003 allowed share for Iran was 78.8 t from a catch for the whole Caspian Sea of 148 t (IRNA, 22 September 2003). The quota for all Caspian caviar in 2004 was 125 tons (www.nytimes.com, downloaded 12 October 2004).

The sturgeons were little used after eggs were extracted for caviar although they were sometimes served in small restaurants along the Caspian coast (personal observations; remarkably tough and tasteless too!). Sturgeons were "haram" in Iran, forbidden for religious reasons as scaleless fish although this has been reversed (Caddy, 1984; Anonymous, 1989; saffron, 2002). Most flesh was exported to Russia (RaLonde and Walczak, 1970b) although some is dried and pickled for local consumption (De Meulenaer and Raymakers, 1996) or eaten freshly grilled (personal observations). Fraser (1834) noted thousands of sturgeon carcasses lying on the Safid River banks, discarded after removal of eggs for caviar and swimbladders for isinglass. Export prices in 1995 ranged from $5.00 per kg of fresh sevryuga fillet to $14.50 per kg for smoked beluga (fil mahi) fillet (Abzeeyan, Tehran, 5(9):V, 1995). Shilat now markets sturgeon head-on or headless, gutted, frozen or in any form required by customers. The average processed weight is about 20 kg for Huso huso, 8 kg for Acipenser gueldenstaedtii (probably includes persicus) and 6 kg for Acipenser stellatus. The meat is served roasted or smoked (Shilat advertisement in Seafood International, December 1995). Research has been carried out in Iran on products derived from left-over parts of sturgeons, the intestines for fish sauce, and skin for gelatin (Sabour et al., 2006).

Capture methods, in the early twentieth century, involved large iron-barbed hooks attached to ropes stretched across the river mouth to foul-hook the sturgeon or, further upstream, poles 6-8 feet long armed with an iron hook used to gaff the sturgeon (Fortescue, 1920). Sturgeons may be caught more recently by large shore seines but mostly they are taken by gill nets set 1-3 km out to sea although De Meulenaer and Raymakers (1996) refer to 300 m fixed nets in rivers with passage space at the sides and bottom as the only authorised method in Iran. Trawling in the sea is not allowed in Iranian waters. Sturgeons are taken from March to June and from September to November in each year (Christie, 1995). The autumn season is best for A. gueldenstaedtii (and presumably A. persicus) while the spring season is best for Huso huso and A. stellatus (De Meulenaer and Raymakers, 1996). Autumn is the main season when the sturgeons migrate to the southern Caspian Sea (De Meulenaer and Raymakers, 1996). The draft "Agreement on the Conservation and Utilization of the Biological Resources of the Caspian Sea" in 1995 prohibited sturgeon fishing in the open Caspian Sea except for traditional methods by Iran near its coast within quota limits (Vinogradov in Glantz and Zonn, 1997).

Gill nets used to capture bony fishes, mainly cyprinids, are responsible for an increase in malformations observed in sturgeons in recent years (Mehdizadeh, 1993). Fins are broken or cut, rostrums (snouts) deformed and net fragments embedded in flesh. Gill nets were prohibited in the Caspian Sea off Iran, except for sturgeons, but during the Iran-Iraq War economic necessity brought back gill netting for bony fishes and cooperatives were established (Habibnejaad, 1993). Gill netter cooperatives were changed to kilka or beach seiner cooperatives and by the end of 1993 no gill nets were allowed in the Caspian Sea. However it took 12 years to overcome objections to banning gill nets by fishermen and in parliament. Problems with excess mortality through inappropriate fishing methods are not new. In the period 1925-1930 the total length of long-lines used in the Caspian Sea was 7-8,000 km while sturgeon nets exceeded 10,000 km. Many fish died in unattended nets or tore lose from long-lines, later to die from hook injuries (Sternin and Dor, 1993). The prohibition of the use of gill nets with a less than 12 cm mesh in 1994 by Iran has conserved stocks along the southern coast of the Caspian. Additionally licenses were restricted and fishing co-operatives closed down in order to control the take (Raymakers, 2002).

Iranian fisheries have taken place mainly in the sea and so a lot of immature fish are caught whereas the former Soviet fisheries took place in rivers where only adults were taken (and ideally could be controlled more easily). However state control in Iran has meant, as noted above, better control over the fisheries and more effective conservation, although poaching does occur.

An attempt has been made to raise sevryuga sturgeon in the central Iranian desert 100 km southeast of Yazd (www.iranmania.com, downloaded 13 March 2003 and other news reports) in a 5000 sq m artificial pond, perhaps more an indication of the desperate straits of the sturgeon populations than anything else.

Pourkazemi et al. (2000) examined the phylogenetic relationships of the 5 sturgeon species in Iran using mtDNA. Huso huso and Acipenser nudiventris showed a close evolutionary relationship as did A. gueldenstaedtii and A. persicus. The latter two species apparently diverged about 1 MYA. Birstein and DeSalle (1998) using molecular techniques found that the Ponto-Caspian species of sturgeons dispersed through the Black, Azov, Mediterranean and Aral seas during the Pleistocene 1.5 MYA and later, the A. stellatus-A. persicus lineage originated 6.0-5.5 MYA in the Upper Miocene-Lower Pliocene, the A. gueldenstaedtii lineage and the Ponto-Caspian sturgeons originated 15 MYA in the Middle Miocene, Acipenser originated and diverged 95-65 MYA in the Upper Cretaceous, and Acipenseridae diverged from Polyodontidae, a related family, 200-135 MYA in the Jurassic.

An important, recent literature source on Caspian sturgeons is Holčk (1989) as well as specific works on Iranian sturgeon biology and fisheries by Rostami (1961b), Vladykov (1964) and Mobayen (1968). The fisheries information in these last three works, relating to techniques and stations, is somewhat dated and not detailed here (Raymakers (2002) gives a map showing Iranian fisheries stations). A general account of sturgeons is given in Birstein et al. (1997) and in Hochleithner and Gessner (1999). Billard (2000) is a recent review of reproduction and associated methodologies used on fish farms. CITES (2001) gives an identification guide in English, French and Spanish, with numerous pictures and diagrams. Pavlov et al. (2001) review the types of spawning migrations carried out by sturgeons. Ruban and Kohodorevskaya (2011) give an historic overview of the Caspian sturgeon fisheries. There are numerous other popular reports and scientific papers on Caspian Sea sturgeons, not all of which can be cited or analysed here. A Bibliography of Sturgeons is given by Y. Keivany and V. J. Birstein at www.geocities.com/keivany/sturgbibl.html. Various manuscript reports on the biology and rearing of the economically important sturgeons have appeared in Farsi, e.g. Abdolhay (1997), Abdolhay and Baradaran Tahori (1998), Baradaran and Abtahee (1998), Fadaee (1997), Kohneshahri and Azari (1974), Moghim et al. (1996), Nasrichari (1993), Pourkazemi (1996), Shafizadeh and Vahabi (1996), etc. Regular symposia on sturgeons are held and extensive presentations and publications result, e.g. The 5th International Symposium on Sturgeons, papers from it being published in Journal of Applied Ichthyology 22(s1)(2006). These works have not all been summarised here because of expense in obtaining copies and because many papers refer to details of aquaculture physiology and biochemistry.

A general Farsi name for these sturgeons is سگ ماهي (sag mahi = dog fish).

Caviar
خاویار

Further information on the catches of sturgeons and production of caviar in Iran can be found in the Species Accounts below. Iran is the second largest producer of caviar, after Russia, with 20% of the world market valued in excess of $50 million (Khajehpour-Khouei, 2000). Azari Takami et al. (1997b) outline the historical development of the caviar trade and Hosseini Seyed et al. (2008) ranks export goal markets for this commercially important product.

Sturgeon roe or eggs are known as caviar and form an expensive delicacy (Bolourchi, 1997). The word caviar may come from Farsi "kaya-dar", "khay-dar" or "khay-var" meaning "having eggs", from خاگ‌آور or khāgāvar for roe-generator, or from "chav-jar" meaning "a cake of strength or power" or "bread of lovers" in allusion to its reputed aphrodisiac qualities; havyar in Turkish means "fish eggs" but the origin of this word seems in some dispute among etymologists and it may be Greek (Georgacas, 1978; Sternin and Dor, 1993; Bolourchi, 1997).

In addition to sturgeon roe, eggs of other species are eaten in Gilan and Mazandaran, where the meal is known as ashpal. The species include Rutilus frisii, Abramis brama, Salmo caspius and less commonly Cyprinus carpio and Barbus sensu lato spp. The roe can be eaten cured as a condiment or when fresh, grilled, steamed or mixed with eggs and fried to form ashpal kuku, a custard-like dish.

The history of the caviar industry in Iran is a complex subject, variously reported in the popular media and in legend. The Russians are said to have obtained writs from Moslem leaders in the Caucasus in the early nineteenth century to the effect that Moslems could not eat these fishes, leaving the valuable caviar fisheries for Russian fishermen to monopolise (Kayhan International, 1 December 1962). The caviar industry was first granted by the Iranian government to Stepan Martinovitch Lianozoff (or Lionosoff, Lianozov) an Armenian subject of Czarist Russia in 1873 (or 1876 or 1879, accounts vary), regularly renewed and later transferred to his only son George. In 1896 the lease was renewed at an annual cost of 450,000 gold francs (Fortescue, 1920). In one version of events, Martin (the grandson of Stepan) disappeared in 1923, kidnapped while meeting two ravishing Armenian sisters, leaving only a letter ceding his rights in the caviar fishery to the Soviets (Tehran Mossavar Magazine, 18 April 1952; Time, 9 February 1953; L'Illustr, Lausanne, 20 January 1955; Tehran Radio, 6 May 1959). Another version simply has Martin selling his rights to the Soviet Government (Mirfendereski, 2000) or refusing to pay during the vicissitudes of the Russian Revolution. In 1919 another Russian subject, Grigor Petrovic Vanitsof rented the southern Caspian fisheries for 20 years but could not fulfill his obligations. A joint Irano-Soviet company, "Mahi Iran", formed under Soviet pressure on the Iranian government, was given a monopoly of the foreign sale of caviar in 1927 (in 1923 the fisheries of Astara, Anzali and Hasan Kiadeh had been occupied by Soviet troops and declared part of the Soviet fisheries). The Irano-Soviet company was run almost entirely by Soviet technicians and the caviar was marketed as of Russian origin (Kayhan International, 27 June 1959; Saffron, 2002). One part of the Persia/U.S.S.R. agreement banned chemical and explosive uses for capturing fish (Mirfendereski, 2000). The fishery was nationalised in 1953 and administered by the Iranian Fishery Company (Sherkat Shilat). Most of the catch was sold to the former U.S.S.R. (Anonymous, 1961b) and Soviet scientists organised caviar production until the Iranian Revolution in 1979-1980 (Taylor, 1997). Greenspan (1989) details more recent skullduggery.

Keyvanfar (1988) described the preparation of Iranian caviar from the various species and the following is taken from that account. Emadi (1994) and De Meulenaer and Raymakers (1996) also give accounts of this process and the kinds of caviar obtained. Sturgeons are alive or very fresh when brought to the processing plant. They are usually killed by a blow to the head. Sex is determined with an awl-shaped instrument inserted into the cloaca, pulling out some ova. The female is split open along the belly and the eggs and the enveloping adipose and connective tissues removed. The eggs are generally about 10% of the body weight. However, an average beluga of 68 kg can yield 18 kg of caviar in Iran (ca. 26%) (V. D. Vladykov, in litt., 1966), and a 40 kg beluga from Iran yielded 8 kg of caviar (20%) (L'Illustr, Lausanne, 20 January 1955). The largest amount obtained from a beluga was 360 kg of caviar (V. D. Vladykov, in litt., 1966). The other species give an average of 6 kg of caviar in Iran. The eggs are separated from the tissues by breaking the ovaries into pieces by hand and delicately pressing the eggs through a 10 x 10 mm screen. This takes only a few minutes. The eggs are then washed in fresh, cold (8-12C) water for 30-40 seconds to remove fragments of ovarian tissue. The eggs are separated from the washing water by collecting them on a very fine mesh screen, the process taking 3-4 minutes. This type of washing is not done with A. stellatus because of the fragility of the egg membrane in this species.

The type and quality of the caviar is determined next and they depend on the colour, diameter and membrane strength of the egg. Large eggs with a strong membrane and a clear, grey, dark brown or gold colour are the best and are packed in metal containers. Small eggs with fragile membranes and sombre colouring are second quality and used for pressed caviar or bulk caviar. Pasteurised caviar is made from eggs with weak membranes since the heat solidifies the membranes. Salt is added at a rate of 4-6% to the weight of the eggs, varying with the season and being higher in the warm summer months. The salt is 99.2% sodium chloride and only 1-10 kg of eggs can be salted at one time so that salting is uniform. Boric acid and borax are added in a ratio of 2:3, comprising 20% of the total salt added, to aid in conserving the caviar. Caviar for export to the U.S.A. is exempt from this addition of boric acid and borax and only salt is used, 100 g for each 1 kg of caviar. The salt is mixed delicately with the eggs by hand for 50-250 seconds. A good salting process is essential for the preparation of caviar and is evidenced by the eggs having small white lines on their surface, the membrane becomes stronger and more resistant, the egg proteins become denser and coagulate, the eggs lose their adhesiveness, liquid stops coming from the eggs, and the density of the brine coming from the process increases. When these factors are detected the salting process is stopped. A salting process which is too long removes too much protein from the eggs and causes the eggs to clump together. A process which is too short removes too little water from the eggs and these eggs lose water gradually over several days in their container and become soft and semi-liquid. The eggs are then separated from the brine on a very fine mesh screen.

The U.S. Customs Service produces a description of caviar for the trade community (www.customs.ustreas.gov/imp-exp1/comply/caviar.htm downloaded on 20 July 1999). Caviar is graded on grain size, colour, flavour and firmness. Gold coloured caviar is the rarest and most desirable followed by light grey. Large grains are preferred over smaller ones.

There is a demand for caviar without borax and boric acid and such chemicals as methyl parahydroxy benzoate and propyl parahydroxy benzoate have been examined in Iran as alternatives (Iranian Fisheries Research and Training Organization Newsletter, 7:3, 1995).

Fresh caviar is not salted and requires careful refrigeration; its shelf life is short, a maximum of six weeks. Lightly salted caviar is called "malossol" from the Russian for "little salt", usually a 2.4% content in Iranian caviar which is very good quality compared to some caviar which contains up to 11% salt. The higher the salt content the longer the shelf life. Chilled malossol kept at -2 to 4C will be edible for up to three months. Pressed caviar is prepared in a similar fashion except the salt content is higher, at 7% in the finished product. It will keep for a long time at 4-8C. Borax gives a longer shelf life too and is less dangerous to human health than the amount of salt needed to give the caviar an acceptable shelf life. Most caviar consumed world-wide is pasteurised as some countries do not accept caviar with borax and higher salt levels are not acceptable to consumers. Pasteurised caviar has a shelf life of 12-15 months (De Meulenaer and Raymakers, 1996). Caviar should not be frozen or pasteurised as this affects the taste. Good quality caviar must be refrigerated. U.S. packaged caviar also contained tragacanth gum according to labels on jars from the 1960s. Bankehsaz (2009) found that the quality and grade of exported caviar can be maintained if storage time is less than 6 months in a -3C cold room. Razavilar et al. (2001) found Iranian caviar to have a good microbial condition during processing and storage in Mazandaran.

The caviar is placed in boxes of 0.5 to 2 kg, each box being filled to within 1-2 cm of the lid. Sternin and Dor (1993) give tin sizes of 0.6 and 1.8 kg with a limited amount of 100, 200 and 300 g tins - most caviar is repacked at its destination in 30 g, 50 g, 125 g, 250 g, 500 g and 1 kg tins and jars). The lid is pressed on centrally to exclude as much air as possible and the excess brine is allowed to drain away by stacking the boxes vertically for 1-15 minutes. One further press is carried out manually, the outside of the box is cleaned, and boxes are stacked in piles of five for 20-24 hours in the cold season (October-March) and 12 hours in the warm season. During this period, the pile of boxes is turned over several times to remove the last traces of excess brine. After one last press on the centre of each box to ensure the lid adheres to the eggs and no air remains, the box is sealed hermetically with a ring of rubber. Well-prepared caviar has lost 4-6% of its initial weight, has a salt content of 3-5% and the eggs are separate and non-adhesive. Caviar in this form will keep for a long time at 0-2C.  Caviar is re-packed in fully airtight tins, slowing down the maturation process for three months after which the caviar deteriorates.

A microbiological analysis of Iranian caviar imported to Turkey has been carried out by Altug and Bayrak (2003) who did not find any pathogenic and toxin producing Salmonella spp. and Clostridium perfringens. Coliforms, bacteria and yeasts showed some high counts, perhaps contamination during production stages.

First quality caviar consists of healthy, non-fragile eggs from one species with a large or medium size. The caviar is dry, of uniform colour - between clear-grey and dark-grey - without odour or abnormal taste. The box is filled within a centimetre of the edge. Second quality caviar has eggs which may be fragile, are of large, medium or small size, their colour varies from clear-grey to black, and they may be damp. Yellowish or brown caviar from A. gueldenstaedtii is acceptable for these two qualities of caviar. Egg size is determined by the cubic centimetres occupied by 100 eggs, e.g. for A. gueldenstaedtii large eggs occupy >1.9 cc, medium 1.4-1.9 cc and small <1.4 cc and for A. stellatus large eggs occupy >1.3 cc, medium 0.9-1.3 cc and small <0.9 cc. Egg sizes are not determined for Huso huso and A. nudiventris. Eggs of the former are much larger than A. gueldenstaedtii eggs while those of the latter are nearly the same size as A. stellatus eggs.

Russian and Iranian caviar tins, beluga, osetra and sevruga (Wikimedia Commons)
Russian and Iranian caviar tins, beluga, osetra and sevruga (Wikimedia Commons)

 

Sturgeon species cannot be readily identified from the size or colour of the eggs making up caviar. Diet, pigmentation of the adult, and age of the fish all appear to influence egg colour. Huso huso eggs are often light to dark grey, Acipenser gueldenstaedtii eggs are blackish to brown or almost golden and A. stellatus eggs are black according to traders. White caviar where the egg has a red spot on it is from albino fish. Light grey beluga and light yellow oscietra caviar are now very rare, in the past being found in only a small proportion of the species population which itself is now in decline (De Meulenaer and Raymakers, 1996). Le Comptoir du Caviar, which markets caviar (www.gourmet-tradition.com/en/comptoir_du_caviar.html, downloaded on 19 March 1999), describes Iranian sevruga as grey to black with fine grains and an iodised taste, Iranian oscietre as grey-black with bronze shades, middle-sized grains, very iodised with a little taste of walnut, and Iranian beluga as very rare, dark or light grey, large grains and a fine and gusty savour.

The single biggest market for caviar is first-class airline passengers. Supermarkets, hotels, restaurants and specialised retailers also market caviar. France consumed the largest amount in the 1990s, about 60-80 t, while Germany consumed 40-50 t. The Shilat packages its product carefully to ensure consumers know the caviar is genuinely Iranian. The large tins in which the caviar is packed keep their contents edible for 12-18 months at -2 to -3C (the oil content and added salt prevent freezing). These tins are sealed in a piece of net which in turn is sealed on both sides with consecutive numbers, placed in a sealed linen bag and then in a wooden box. Each tin is also marked with the loading station number (where the fish are brought after capture to have their caviar removed) and also the number of the individual fish scratched on the side. Tins are shipped by air in "cooltainers" which have their own refrigeration unit. These large tins are vacuum-packed into smaller ones in packing centres in Europe (Christie, 1995). The main market in 2000 was Japan to which 30% of Iranian production was exported. Permanent markets in Europe are Switzerland, Germany, France, Luxembourg and Spain (I.F.R.O. Newsletter, 26:3, 2001) and the European Union is often the biggest importer of Iranian caviar. Iran was the top exporter of caviar in the year 2000 at 71.5 t valued at $34.4 million (IFRO Newsletter, 28:2, 2001). This is a value increase of 17% although the amount was less than in 1999 at 84.9 t. In 2002, 87% of caviar came from Iran (www.caviar.ru/english/digest.htm, downloaded 12 December 2002) although IRNA (8 December 2002) gives a figure of of almost 50%. The caviar export quota was 50,505 kg for Iran in 2006 (iran-daily.com, downloaded 28 July 2006) or 44.3 t (Iran Daily, 11 September 2006).

Iranian caviar sold in major airports like Heathrow in London comes in several kinds. Caviar House markets imperial, which has large gold grains and was previously reserved for the Shah's family (from Acipenser persicus); beluga, light to dark grey and large grained; royal black consisting of large deep-black grains from a 20-40 year old osetr; "oscietre", which is dark grey-brown to a golden yellowish; classic grey, a pale grey with large grains; and sevryuga, which is dark grey and fine grained. Prices vary with quality and time as shown below (personal observations):-
 
Imperial Beluga Royal Black Oscietre Classic Grey Sevryuga
December 1993
50 g 82 76 48 36 38 23
1000 g 1411 1318 819 621 656 399
September 1995
50 g 94 101 54 48 40 36
1000 g 1640 1759 939 836 697 630
September 1997
50 g 89 88 53 47 39 34
1000 g 1536 1540 912 812 680 590
November 1999
50 g 140 160 75 60 65 53
1000 g 2420 2770 1312 1060 1138 920
November 2000
50 g 184 208 114 95 99 79
1000 g 3541 3987 2177 1818 1894 1527
April 2002
50 g 184 208 114 95 99 79
1000 g not given not given not given not given not given not given 

The types of caviar listed changed in 2003 as follows:-

 
Imperial XO Beluga Beluga XXL Royal Black Royal Black XL Oscietre Gold Classic Grey
March 2003
50 g 289 160 309 11 6 197 119 125

The types of caviar listed changed in 2004 as follows:-

 
Imperial XO Beluga Beluga XXL Royal Black Royal Black XL Classic Grey Sevruga Oscietre Imperial
September 2004      
50 g 145 160 195 88 114 66 56 75 98
100 g 275 318 385 175 225 129 110 149 195
200 g 540 619 750 340 435 247 221 297 385

The types and weights of caviar listed changed in 2006 as follows for "Prestige Selection":-

 
Beluga Royal Black Classic Grey Sevruga Oscietre Oscietre Gold*
March 2006      
50 g 155 125 105 95 120 130
125 g 380 305 255 230 295 320
250 g 750 595 495 450 580 630

* = golden-coloured eggs from a mature oscietre.

The types and weights of caviar listed changed in 2006 as follows for "Prunier":-

 
Traditional Saint James Great American Paris Heritage
March 2006    
50 g 65 85 95 120 155
125 g 155 205 230 295 380
250 g 305 405 455 585 755
500 g 605 805 905 1165 1505
March 2007 (500 g not listed)          
50 g 75 110 (not listed) 120 170
125 g 185 270 (not listed) 295 415
250 g 370 535 (not listed) 585 830

The types and weights of caviar listed changed in 2006 as follows for "Private Reserve":-

 
Royal Black XL Imperial XO Beluga XXL
March 2006
50 g 135 145 195
125 g 330 335 480
250 g 650 695 950

Prices for these brands were not listed in March 2007, and were only available on request, indicative of both scarcity and constantly changing prices. Names of the different types of caviar keep changing so it is difficult to track price increases. In November 2008, beluga caviar from Caviar House was selling for 2170 for 250 g and other types had also continued to increase in price, often dramatically. Curiously, in July 2010 under "Caspian Sea caviar" beluga was selling at 1340 per 250 g. In 2011, all available caviar was Russian or farmed. In 2012, prices were for 250 g of Beluga and Imperial caviar 1650 and for Royal Black and Oscietre 790.

Taylor (1997) gives prices in Deutschmarks (DM) per kilogramme net weight (no duty paid) for Iranian caviar over 12 years including the approximate "bazaar" or illegal price for smuggled caviar (note also that A. gueldenstaedti probably includes A. persicus):-

 
Year Huso huso A. gueldenstaedti A. stellatus "Bazaar"
1983 540 408 341 200
1984 600 424 400 180
1985 675 465 404 180
1986 650 460 345 200
1987 650 414 325 180
1988 1630 445 310 180
1989 2600 510 345 220
1990 1596 432 304 220
1991 1600 450 337 180
1992 1600 470 345 160
1993 950 435 345 160
1994 950 500 355 80

Taylor (1997) also compares demand from western markets with supply from Iran; for Huso huso demand is 0.2 tonnes while supply is 2.0 t, for A. gueldenstaedti type I.A 2.0 t and 0.5 t, for A. gueldenstaedti type I.B 60.0 t and 40.0 t, for A. gueldenstaedti type II 15.0 t and 10.0 t, for A. stellatus I 100.0 t and 30.0 t, and for A. stellatus type II 100.0 t and 25.0 t.

Friedland (1986) gives a variety of recipes for caviar dishes.

Rehbein (1985) and Keyvanfar et al. (1987) studied soluble caviar proteins of sturgeon species including A. gueldenstaedtii, A. stellatus, A. nudiventris and Huso huso. They were able to distinguish the species on this basis and thus provide a means of detecting fraudulent caviar. Rezvani Gilkolaei (2002) used DNA PCR amplification and RAPD markers to identify caviar, in particular that of the endangered Acipenser nudiventris whose caviar has been substituted for more expensive caviar of A. gueldenstaedtii and A. persicus. Rehbein et al. (2008) tested and reviewed different methods for identifying caviar by species, including DNA, differential scanning colorimetry and determination of stable isotopes. Gessner et al. (2008) were able to distinguish between farmed and wild sturgeons based on fatty acid composition and recommend use of specific fatty acids as additives in the formulated diets of farmed fish. However, Ludwig (2008) reviewed methods of identifying caviar and other sturgeon products and detailed difficulties. No single method met the criteria he established (species-level identification, population identification, wild versus aquaculture, age of caviar). Cost was also a factor. Keyvanfar (1984) was unable to find genetic polymorphism in erythrocytes of the four species listed above using serological techniques. Moghim et al. (2012) isolated and characterised microsatellite loci to assist in identifying population structure of sturgeon species for use in conservation work.

Genus Acipenser
Linnaeus, 1758

This genus is characterised by a small, transverse mouth (large and crescentic in Huso), by the gill membranes being joined to the isthmus and not to each other (joined to each other and free of the isthmus in Huso), by a rounded or elongate snout, and cylindrical barbels. Bani et al. (2008) give details of brain morphology in Acipenser stellatus and A. persicus that suggest sturgeons have evolved different sensory strategies to cope with life in the deep sea.

There are 16 species in the genus and 4 are reported from Iran.

Ventral view of heads of Huso huso, Acipenser nudiventris, A. gueldenstaedtii

Ventral view of heads of Huso huso, Acipenser nudiventris, A. gueldenstaedtii
and A. stellatus (A. persicus is similar to A. gueldenstaedtii)

Acipenser baerii
Brandt, 1869

Introduced to the Caspian Sea basin by Soviet authorities (Karpevich and Lukonina, 1971; 1972; McNeil, 1979) but no records from Iran.

Acipenser gueldenstaedtii
Brandt and Ratzeburg, 1833

Common names

چالباش (= chalbash or short head), تاس ماهي (= tas mahi or bald fish; this term includes A. gueldenstaedtii, A. persicus and A. nudiventris for large eggs, in fisheries statistics), تاس ماهي روس (= tasmahi-ye Rus or tasmahi-e-russ), تاس ماهي ايراني (= tas mahi Irani), osiotra, osyetra, سگ ماهي (sag mahi), ماهي خاويار (= mahi-ye kaviar, meaning caviar fish), kaviari rusi.

[russkii osetr or Russian sturgeon in Russian; nere or rus neresi in Azerbaijanian; bekra or bekre balyk in Turkmenian].

Systematics

This species was originally described in part from the Volga, Ural and Terek rivers of the Caspian Sea. Sometimes spelt gldenstdti, but accents on letters are not used in Latin scientific names. Birstein et al. (1997) and Reshetnikov et al. (1997) spell the name gueldenstaedtii, regarding the double "i" ending correct as opposed to the emended single "i" which appears in much recent literature.

Acipenser gueldenstaedti persicus natio kurensis Belyaeff, 1932 was described as the Kura River subspecies but see below under Acipenser persicus. Comparison of serum proteins have shown antigenic characteristics distinguishing Volga and Kura River stocks in the Caspian Sea, matched by morphometric characters.

The fishes identified as A. gueldenstaedtii in Iran may well be almost entirely A. persicus, although this remains to be determined. Consequently data on morphology and biology are confused in many accounts. The distinction of A. persicus is questioned by authors (see below).

Some specimens have strong spines on the scutes and have been described as morpha aculeatus Lovetzky, 1834 although this has no nomenclatural status.

Birstein and Ruban (2004) and Birstein et al. (2005) state that this species has at least three, morphologically indistinguishable, genetic forms in the Caspian Sea. These are the pure form, one similar to A. baerii of Siberia, and one to A. naccarii of the Adriatic, with competing hypotheses to explain this. The most likely hypothesis is that the Caspian forms are closely related to the ancestral forms of the three species, evolving first as subdivisions of the original Caspian Sea population and then moving to different geographical areas when the Caspian was connected to them.

Pourkazemi et al. (1999; Rezvani Gilkolaei, 2000) found two distinctive genotypes and therefore populations of A. gueldenstaedtii in Iranian waters using molecular techniques. This species and A. persicus showed great degrees of similarity in a phylogenetic analysis (Iranian Fisheries Research and Training Organization Newsletter, 14:4-5, 1996; Pourkazemi et al., 2000). The common origin of the two species was about 1 million years ago (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 61-62, 1997; Pourkazemi et al., 2000).

Key characters

This sturgeon has a short snout (less than 60% of head length) with a rounded tip in contrast to the long snout (>60%) and pointed tip in A. stellatus. Huso huso has an unusual, crescent-shaped mouth and continuous gill membranes forming a fold on the isthmus and A. nudiventris has a continuous lower lip and usually more than 50 lateral scutes. Closely resembling A. persicus, it is distinguished from that species by the short and blunt snout, yellowish-white belly and golden-brown back. A drawing in Vlasenko, Pavlov and Vasil'ev in Holčk (1989) of the two species has a snout length in head length of 4.3 as opposed to 3.2 for Acipenser persicus but figures of snout length in total length overlap for the two species. The interorbital distance is much less in the Persian sturgeon (29.2-30.5% of head length) than in A. gueldenstaedtii (Artyukhin and Zarkua, 1986) but in small specimens examined by me from Iran, some had gueldenstaedtii interorbital distance and persicus snout length. There is a colour plate and line drawings of the heads of the two species from the Black Sea in Birstein et al. (1997:8, 220).

Morphology

The lower lip is interrupted at its centre. Barbels are not fringed, lie nearer the snout tip than the mouth, and do not extend back to the mouth. Sheibani (2003b) described the posterior alimentary canal in this species.

Dorsal fin rays 26-51, anal fin rays 18-35. Gill rakers 15-36. Dorsal scutes 5-19, lateral scutes 21-50 and ventral scutes 6-14. There are rows of smaller star-shaped scutes between the dorsal and ventral rows in some fish, rounded in this species and more triangular in A. persicus. The chromosome number is 2n=250 8, 2n=249 2, 2n=247 7 or 2n=258 4(Klinkhardt et al., 1995; Havelka et al., 2011).

Sexual dimorphism

Females are larger than males of the same age.

Colour

The back is usually golden-brown but may be olive-grey to dark green, the flanks grey-brown, and the belly yellowish-white or rarely a lemon yellow. Young are blue dorsally and white ventrally.

Size

Attains 160 kg and 2.36 m, perhaps as much as 4 m although not confirmed (Machacek (1983-2012), downloaded 27 July 2012). In Iran, fish identified as this species (see Systematics) averaged 16-20 kg and 1.4-1.6 m in the 1950s (Farid-Pak, no date). Tsepkin and Sokolov (1971) state that Safid River fish reach 2.42 m. De Meulenaer and Raymakers (1996) give 200 kg and an average length of 2 m.

Distribution

This species is found in the Caspian Sea, particularly in the Volga River basin, as far as Moscow in the past. Very small numbers are caught in the Kura and Astara rivers. Also found in the Black Sea basin. Khodorevskaya et al. (2001) review abundance and distribution in former Soviet waters of the Caspian Sea. It is less common than Acipenser persicus in Iranian waters.

In Iran, it is recorded from the Astara River in the west to the Gorgan River in the east (but see Systematics). Reported recently from such rivers as the Atrak, Gorgan, Gharasu, Tajan, Babol, Haraz, and Safid, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea (Abbasi et al., 1999; Kiabi et al., 1999; Abdoli and Naderi, 2009). V. D. Vladykov's field notes in the early 1960s reported it from Kopurchal, Khadjenafas, Tazeabad, 12 Bahman, Nevissi, Izadeh and Hasan Kiadeh. Access to many rivers must now be restricted by reduced water flow, construction, weirs, dams, irrigation canals and pollution.

Zoogeography

Presumably a relict of the isolation of the Caspian and Black seas from the Mediterranean-Atlantic.

Habitat

There is no marked seasonal variation in depth distribution in the south Caspian Sea in contrast to the middle Caspian. This species is found over sand or sandy-silt bottoms in a temperature range of 2.3-24.8C and a salinity range of 6.28-14.34 in the sea. Farabi et al. (2011) examined experimentally salinity tolerance in juveniles and found it, and survival, to increase with age. It approaches closer to the coast in winter (February) than other sturgeons because it favours colder temperatures. It is found in numbers down to 50 m with only the occasional specimen being caught below this depth (Legeza, 1972; 1973). Brackish water is favoured because of food concentrations. High oxygen concentrations are needed, 6-7 mg/l for adults, although larvae only require a minimum of 1.56 mg/l at 20C. Reproduction in the Kura ceases when temperatures reach 26C. Eggs are sensitive to oil concentrations of 0.5-1.0 mg/l. Levin (1997) reports concentrations on the western shelf of the Caspian Sea during winter, as far south as Azerbaijan, at depths of 5-24 m.

Age and growth

Veshchev and Novikova (1986) and others have recently studied the spawning run of this species in the Volga River and found fish from 7 to 39 years old with 87.9% 13 to 27 years old. The spawning population comprises 32 age groups therefore. Males dominate at 63.6%. Males vary in length from 101 to 185 cm and weigh 3 to 38 kg and females from 116 to 200 cm and 9 to 46 kg. Most males begin to reproduce at 11-13 years while females begin at 12-16 years. Growth can be rapid, young-of-the-year reaching as much as 35 cm by autumn. Life span exceeded 48 years in the past. Khodorevskaya et al. (1993) cited in Levin (1997) gives Volga River spawning ages of 8 to 35 years with females 6-8 years older than males. Females have an average weight of 26-29 kg and a length of 136-163 cm; males are 12.0-14.5 kg and 130-134 cm. Females mature at 10 years, 2-3 years later than males. Minimum spawning intervals are 2-3 years for males and 3-4 years for females.

Von Bertalanffy growth parameters in Iranian females are L = 201 cm and K = 0.073 or 192 cm and 0.082 and for males 189 cm and 0.092 depending on the methodology used. Total mortality (Z) was 0.33-0.67 for females and 0.46-0.82 for males, natural mortality (M) was 0.05 for females and 0.06 for males, fishing mortality (F) was 0.62 for females and 0.39 for males, and optimum fishing mortality was (F) 0.21 for females and 0.37 for males (Iranian Fisheries Research and Training Organization Newsletter, 16:4-5, 1997).

Food

This species is primarily a mollusc eater (Polyaninova et al., 1999) but also takes crustaceans such as chironomids and gammarids and small fishes such as gobies (Gobiidae) and Clupeonella caspia. The introduced species of mollusc, Abra ovata, polychaete, Nereis diversicolor, and crab, Rhithropanopeus harrisii are now important diet items at 49.3%, 12.3% and 9.2% respectively in the Caspian Sea. The importance of oligochaetes like Nereis and Enchytraeus albidus in the diet of sturgeon species is recognised in Iran and studies on their ecology have been carried (IFRO Newsletter, 28:3, 2001). In rivers, fingerlings feed on various benthic organisms. Hajimoradloo et al. (2002) examined the diet of juvenile fish taken in beach seines from the Miankaleh peninsula in Golestan and compared it with the diet of A. persicus. The latter favoured cumaceans while A. gueldenstaedtii favoured gammarids. Both species had more empty stomachs in autumn and less in winter. A. gueldenstaedtii had more empty stomachs in all seasons than A. persicus. The food niche width was less in A. gueldenstaedtii and food overlap was highest in winter and lowest in spring.

Reproduction

Spawning migrations in sturgeons are triggered by temperature, daylength and flood discharge. This has been discussed more fully by Barannikova (1972) along with the effects of dams on this complexly timed, hormonal process. In northern rivers the water temperatures are 8-18C (Artyukhin and Zarkua, 1986). The adult loses 25-30% of its weight after spawning and females are only ready to spawn again after 4-6 years and males after 2-4 years.

The spawning run in the Kura River is complex and four "races" have been recognised (Gerbilskii, 1955; Berg, 1959). These are early and late vernal, spawning in their year of entry, and summer-arriving and autumn-arriving hiemal which overwinter to spawn the following spring. The chief spawning period in the Kura River is from the end of May to the beginning of July (Zakharyan, 1972). (Note that this may in fact apply to A. persicus).

In the Volga River, A. gueldenstaedtii has a run beginning at the end of March or beginning of April at 1-4C, peaking in July. Migration speed in the Volga is 18.1-22.6 km/day. Eggs are laid on gravel or stone beds at 4-25 m depths and a current velocity of 1-1.5 m/sec. in the Volga River. Some eggs are laid in shallower, flooded areas. Egg incubation is optimal at 9-15C. The downstream migration of spawned out fish in the Volga begins in the second half of May and peaks in June and July. Levin (1997) summarises the migration of Volga River fish as follows. The small population of the early spring race enters the Volga delta in April-May and migrates upriver for 600-700 km before spawning in May-June at 12-15C. The late spring race migrates to spawning sites in May-June, spawning in July-August at 19-22C. In June-July the winter race enters the delta but only migrates upriver in the next summer. In August-October the late winter race enters the river. These winter races overwinter in deep parts of the river and spawn in April-May at 9-13C.

Volga River sturgeons had a fecundity of 332,900 eggs in one study (Veshchev and Novikova, 1986), elsewhere reported up to 1,165,000 eggs for the Volga. The Safid River sturgeon fecundity is said to be less (this may be A. persicus). Eggs are brownish-grey and ovate, up to 3.3 x 3.8 mm in dimensions. A 150 kg fish yielded 5 kg of caviar (IFRO Newsletter, 29:4, 2001).

The sexual cycle lasts 2-3 years on the Iranian coast and is described by light microscopy in Hedayatifard et al. (2009).

The caviar of this species comprises 4-5 kg on average, making up 16% of the body weight in Iran. In Mazandaran fish enter rivers in autumn, overwinter and spawn in spring (Iranian Fisheries Research and Training Organization Newsletter, 9:6, 1995).

Parasites and predators

Niak et al. (1970) report infestations of the ciliate Trichodina sp. in sturgeons (species unspecified) in breeding ponds in Iran. Golvan and Mokhayer (1973) describe Corynosoma caspicum as a new species from this and other sturgeon species in Iran. Mokhayer and Anwar (1973) report the following parasites from Iranian sturgeons in general. These are the protozoan Trichodina reticulata, the coelenterate Polypodium hydriforme, the trematodes Skrjabinopsolus acipenserinus and S. skrjabini, the cestodes Amphilina foliacea, Bothrimonus fallax and Eubothrium acipenserinum, the adult nematodes Ascarophis ovotrichuria, Cyclozone acipenserina and Cucullanus sphaerocephala, the larval nematodes Contracaecum squalii, Anisakis schupakowi and Eustrongylides excisus, the acanthocephalans Leptorhynchoides plagicephalus, Pomphorhynchus laevis and Corynosoma caspicum, the annelid Piscicola geometra and the crustacean Pseudotracheliastes stellatus. Polypodium hydriforme destroys the eggs of sturgeons, up to 80% of the gonads, rendering reproduction insufficient to maintain the species. Amphilina foliacea causes parasitic castration in sturgeons. Many of the parasites provoke anaemia or block the intestine when numbers are high. Pomphorhynchus laevis is capable of piercing the intestine. Eustrongylides excisus produces stomach abscesses. Ectoparasites take blood but also facilitate attack by bacteria and fungi. On fish farms, Trichodina reticulata can cause high mortalities while having no apparent effect under natural conditions. Parasite numbers are controlled on fish farms by immersing the sturgeons in salty water to remove ectoparasites, by feeding food items known not to be carriers of parasites and avoiding such natural foods and intermediate parasite hosts as amphipods. Mokhayer (1976b) reports gas bubble disease in Iranian sturgeons without specifying the species of sturgeon as well as the monogenetic trematodes Diclobothrium armatum and Nitzschia sturionis, the digenetic trematodes Skrjabinopsolus acipenseris and S. skrjabini, the cestodarian Amphilina foliacea, the cestodes Bothrimonus fallax and Eubothrium acipenserinum, the nematode larvae Anisakis schupakowi, Contracaecum squalii and Eustrongylides excisus, and the nematode adults Ascarophis ovothricuria, Cucullanus sphaerocephala and Cyclozone acipenserina, the acanthocephalans Corynosoma caspicum, Leptorhynchoides plagicephalus and Pomphorhynchus laevis, and the crustacean Pseudotracheliastes stellatus. Hajimoradloo (2002) records the nematode Cystoopsis acipenseris in juveniles at a frequency of 6.42%. Sattari et al. (2002) record Cucullanus sphaerocephalus, Eustrongylides excisus, Skrjabinopsolus semiarmatus, Leptorhynchoides plagicephalus, Anisakis sp. and Corynosoma strumosum, the fauna being similar to other sturgeons because of their piscivorous feeding. Hajimoradloo and Ghorbani Nasrabadi (2003) found the prevalence of metazoan parasites in juveniles of this fish in the southeast Caspian Sea to be 8 species with Anisakis larvae the highest at 13.3%. Pazooki and Masoumian (2004) report on blood parasites form fish caught at Anzali, recording Cryptobia acipenseris and Haemogregarina acipenseris. These parasites caused no pathological effects in the wild fish but can lead to severe infections and cause anaemia on fish farms. Sattari and Mokhayer (2005a; 2005b) recorded the occurrence of parasites in this species from the Iranian southwestern and central coast of the Caspian Sea. The species found were the nematodes Cucullanus sphaerocephalus, Eustrongyloides excisus and Anisakis sp., the acanthocephalans Leptorhynchoides plagicephalus and Corynosoma strumosum, and the digenean trematode Skrjabinopsolus semiarmatus. General conclusions were that the diversity of parasites was less in Iranian waters than in the northern Caspian Sea, perhaps a reflection of the more varied habitat, its productivity and the carbonate ions differing between the two regions. The diversity of parasite seems to have declined over time also, perhaps as a result of unfavourable environmental conditions, particularly in the freshwater ecosystem which limits the waters available for spawning and parasite acquisition. Barzegar and Jalali (2009), in their summary of crustacean parasites of Iranian fishes, recorded Pseudotracheliastes stellatus from this sturgeon.

A wide range of fish species are predators on the eggs of this sturgeon and the young are taken by Silurus glanis, Alosa spp., Huso huso, and gobiids.

Economic importance

Chalbash have been fished in the Caspian Sea for at least 6000 years based on excavations at a Neolithic site on the eastern Caspian coast (Tsepkin, 1986).

This particular species is fished primarily in the months of September and in April-May in Iran. Caviar yield was 4-7 kg per female in the 1950s (Farid-Pak, no date). Yields from 1963 to 1967 of meat (and caviar) were 794.2 tonnes (69.3 tonnes), 918.2 (66.7), 849.0 (71.8), 974.6 (72.8), and 977.1 (75.9) respectively (RaLonde and Walczak, 1970b). A commercial house maintains (1995) that this species comprises 27% of the total catch. These data presumably include or are almost entirely A. persicus in Iran. Spring-caught chalbash produce 2-3 kg of eggs per fish while those caught in the fall have egg weights of 3-4 kg. The former are more suitable for pressed caviar than the higher priced grain caviar made from the larger eggs of fish caught in fall (Vladykov, 1964). Figures for tas mahi (this species plus A. persicus, and also A. nudiventris when eggs are large) average yearly catches in Iran were given by Vladykov (1964) for the period 1927/28-1931/31 to 1957/58-1961/62. Body weight varied from 264,105 kg (36.9% of total sturgeon catch) to 842,050 kg (78.9%) while caviar weight varied from 33,098 kg (69.3%) to 159,931 kg (85.1%) although the lowest percentage share of caviar for any of the five-year periods in tas mahi was 28.6%. The category of tas mahi provided the majority of eggs for caviar up to 1946/1947 (50-89%) but this fell to 29-31% for the period after 1949/1950 in Vladykov's data. Earlier data from Nevraev (1929) listed as A. gueldenstaedtii and A. nudiventris combined for the Astara region of Iran gives catches of 2002 to 9176 individuals for the period 1901-1902 to 1913-1914, for the Safid Rud region 26,721 to 54,257 individuals for the period 1899-1900 to 1913-1914, for the Mazandaran region 4065 to 8818 individuals for 1906-1907 to 1913-1914, and for the Astrabad (= Gorgan) region 2988 to 6044 individuals for 1902-1903 to 1913-1914. The capture fishery for tas mahi (A. gueldenstaedtii, A. persicus and A. nudiventris) was 89%, 4.2% and 6.2% respectively in 1973 but by 1993 had changed to 27%, 69% and 4% due to fingerling production of A. persicus (Abdolhay and Tahori, 1999). The stock of this species in Iranian waters in 2001 was 9.4 million (0.64 million) specimens comprising 12,900 tonnes (2074 t) with a commercial stock of 220 t (223 t) (Ivanov and Kanunin, 2001; figures in parentheses from text which does not agree with table).

Catches of this species in the southern Caspian Sea have declined from 837 t and 602 kg/boat/day in 1971-1972 to 57 t and 0.34 kg/boat/day in 1999. Young fish decreased in the decade prior to this study while older fish dominate at present (Moghim, 2004a). A sharp decrease in sea ranching of fingerlings and a consequent decrease in young fish abundance, will cause a a considerable decline in future catches.

Dry-smoked flesh (balyk) is especially favoured in Russia where this species occupies the first place in catches. Catches in the period 1898-1913 in the northern Caspian reached 10,000 tonnes a year only to decline through overfishing. The ban on sea fishing in 1941, restricting catches to rivers where they could be more closely controlled, led to a rebound of stocks and by 1977 a record catch of 11,980 tonnes was made.

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaculture and as food.

Conservation

Sturgeons generally are conserved by fish farming and release of young and fry, attempting to augment natural populations. Stroganov (1968) reviews Russian fish farming methods. Derzhavin (1923) reported release of 7,620,000 fingerlings in the Safid River of Iran in 1923. Release of unfed sturgeon fry was discontinued in Iran in 1965 as unproductive. A hatchery produced annually 5.5 million sturgeon juveniles at 3-5 g each (McNeil, 1979), comprising the species A. stellatus and A. gueldenstaedtii (the latter presumably includes A. persicus). The Sad-e-Sangar (Dr. Beheshti or Martyr Beheshti) Fish Farm or Hatchery 27 km from Rasht in Gilan produced 14-15 million sturgeon larvae in 1987 and up to 3 million 2-3 g sturgeon are produced annually (Petr, 1987). Fingerling production from four hatcheries in Iran reached a record high of 12 million fish in 1995-1996 and with a new hatchery in the Gorgan region is expected to reach 20 million fingerlings (Abzeeyan, Tehran, 7(6):V, 1996). IRNA reported on 31 August 1998 that 24 million fry had been raised since March of that year, a 15.3% increase over the previous year and 20 million fry are now released each year. The Shahid Rajaee Fish Aquaculture Center at Sari, Mazandaran produces 5.5 million sturgeon fingerlings annually, released in 13 Caspian Sea rivers (IFRO Newsletter, 28:3, 2001). The only species not produced is Huso huso and the most popular is Acipenser persicus for its better quality caviar. The young are fed on daphnia and later oligochaetes (white worms). Fingerlings may be grown to 10-15 cm length before being released in the Safid River about 20 km from the sea to imprint on the river. In 1987 2.28 million fingerlings were released and in 1993 6.5 million from the Beheshti Hatchery. In 1993 a closed system fish culture plant was opened at this hatchery to produce at least 5 million sturgeon fingerlings annually (Abzeeyan, Tehran, 4(9):IV, 1993; see also Anonymous (1993c)). A later report mentions culture of Huso huso in addition to the sturgeon species mentioned above for the Dr. Beheshti Sturgeon Hatchery, and production of fingerlings exceeded 60 million in 1991, the best year from 1973 to 1993 (Abzeeyan, Tehran, 5(3 & 4):IX-X, 1994).

About half a million fingerlings were produced in autumn 1995 in Mazandaran province (Iranian Fisheries Research and Training Organization Newsletter, 9:6, 1995). In 1996, it was expected that 15 million sturgeon fingerlings would be produced from hatcheries, the main species being Acipenser persicus, Acipenser stellatus and Huso huso. Fingerlings would be 3-5 g in weight when released in the Safid River (Abzeeyan, Tehran, 7(2):IV, 1996). The Shaheed Beheshti Fish Propagation and Rearing Complex of Shilat (Iranian Fisheries Company) produced 9 million sturgeon fingerlings in 1997, each 3-5 g, for restocking (Bartley and Rana, 1998b). Eggs are incubated for 5-7 days. Fingerlings are fed on live Artemia, Daphnia and oligochaetes in 2.5 sq m circular tanks from day 15 (60-80 mg) and then in earthen ponds for 50 days to the 2-3 g size. The fingerlings remain in the release river for 10-15 days before entering the Caspian Sea.

The International Sturgeon Research Institute, which opened in 1994 near Rasht, released 22 million fry in 1996-1997 (Bartley and Rana, 1998b). The Institute carries out varies research programmes, e.g. on the histology of the gonads of reared sturgeons which have been found to be the same as sturgeon in nature (Bahmani and Kazemi, 1998).

Abdolhay and Tahori (2006) give fingerling production for this species as:-

Process/Year 2000 2001 2002 2003 2004
Female broodstock captured 81 74 65 0 31
Injected broodstock 29 24 19 0 10
Spawning rate * (%) 89.6 79 66 0 80
Fertilisation rate (%) 70 55.5 49 0 71
Survival rate in incubators (%) 53 53.9 48 0 75.1
Survival rate in tanks (%) 80 70.1 68 0 79
Stocking density in ponds (fish/ha) 88,333 74,580 63,752 0 65,000
Survival rate in ponds (%) 65 79 71 0 65.1
Fingerling production (x 1000) 1327 447 1816 0 617

* Rate of response to hormone injection

An experimental approach to conservation of stocks has been the raising of sturgeon artificially to a size where they produce caviar. The Shahid Beheshti sturgeon aquaculture centre raised a member of this species to 121 cm, 11.5 kg and 8 years of age when it yielded 1.4 kg of caviar (Iranian Fisheries Research Organization Newsletter, 37:2, 2003; Iranian Fisheries Research Organization Newsletter, 40 & 41:4, 2004).

Shevchenko et al. (1999) summarise rearing technology for A. gueldenstaedtii in Iran. Fingerlings are raised on artificial feeds in 1-4 cu m plastic tanks for up to 180 days. A mean mass of 120 g is attained, with a maximum of 300 g. Growth rate of different age groups varied from 1.59 to 0.56% and daily weight gain was from 4.23 to 1.42%. The mean daily increment was affected by stocking density, daily rations, oxygen content, feed quality and maintenance of feeding routine. Falahatkar and Amini (2003) give further details on propagation from broodstocks including maturity duration, oocyte diameter and weight, motility and density of spermatozoids, time taken to reach 4 and 16 cell divisions, incubation duration, fertilisation percentage achieved at each stage, mortality rate during incubation, number of larvae obtained from each broodstock, number of larvae per gramme, weight of each larva, and morphometric parameters and age for each broodstock. Akrami et al. (2005) found cladocerans, copepods and chironomid larvae were secondary prey items of fingerlings in one earthen pond with ostracods occasional prey, while in another pond all these were secondary prey. Condition factor and growth decreased as weight and length of fingerlings increased. Growth was was negatively allometric (b<3).

De Meulenaer and Raymakers (1996) give figures for Iranian hatchery production from 1983 to 1992 as 1.03 to 6.61 million fingerlings (mean 2.9 million) although mature adults are becoming increasingly difficult to catch for stripping of eggs and sperm. These Iranian hatcheries are much smaller than Russian ones which produced about 25 times this number on average annually from the Volga River hatcheries alone.

There is an extensive Russian literature on how to raise sturgeons, e.g. Mil'shtein (1957; 1972), Marti (1972), Barannikova (1987) and Dettlaff et al. (1993). A recent (1984-1986) estimate of this species in the Caspian Sea is 47.7 million fish with 24-28% produced by artificial means.

All sturgeons are particularly threatened on the spawning migration when they concentrate in rivers (Rochard et al., 1990). Sturgeons in the Aras River on the former Soviet-Iranian border, for example, are threatened by dams and water diversion schemes (Zakharyan, 1972). However this is not an annual migration so the populations are not subject to loss every year. The common problems encountered by all Caspian sturgeons are dams and weirs which block reproductive migrations of adults upriver and also of young and adults returning to the sea, water abstraction for irrigation which reduces flow or even dries up a river, degradation of the river bed by extraction of gravel for construction or the change in silt deposits by the filtering effects of dams, increased water clarity enables predators to be more effective changes in the oxygen and temperature regimes caused by water abstraction, retention of water behind dams or untimely release from dams, pollution, attraction of adults into irrigation channels by their strong water flow and changes in the invertebrate fauna on which the young feed in rivers (Vladykov, 1964; Anonymous, 1970c; Whitney, 1979; Rochard et al., 1990). Variations in Caspian Sea levels also had effects (Khodorevskaya et al. 1997). For Huso huso these include lowered accessibility to feeding sites and variations in food abundance which lead to decreases in relative weight gain and to a halving in the number of females. The growth and survival of juvenile Acipenser gueldenstaedtii in the Volga River delta during their first winter is affected by lower water levels.

Stocks in their sea life were fairly safe until trawling was introduced. There are restrictions on trawling in the sea to reduce loss of young sturgeons (Ricker, 1970) and trawling is banned in the territorial waters of Azerbaijan (Markarova and Alekperov, 1989). It has been suggested that the Caspian Sea level should be maintained at -28.5 m or above to retain water productivity on which sturgeons ultimately rely. A 1 m decline in level can reduce fish food supply by 60% and hinders migration to feeding grounds, another 20% loss (Petr, 1987).

The institution of closed seasons for fishing and restrictions on techniques used to limit juvenile catches have been implemented in the former U.S.S.R. The fine for illegal possession of a Huso huso was about 280 in 1977. Fish lifts have been built on the Volga River about 5000 km upstream from the Caspian Sea to transport sturgeon around the Volgograd Dam. The system transports about 10-20% of migrating Huso huso, Acipenser gueldenstaedtii and A. stellatus but is relatively inefficient (Rochard et al., 1990). The poor situation is compounded by the lack of suitable spawning conditions above the dam and by adults having to migrate downstream through the dam's turbines. The turbines have wide blades and rotate slowly so most adults cannot make it through although the young are short enough to survive the transit. Khodorevskaya et al. (1997) summarise the decline in catches of this species after the regulation of the Volga River flow by the Volgograd Dam, built in 1958-1960, which cut off as much as 80% of the spawning grounds.

In Iran baiting hooks with oilcloth or fish was banned in 1952 as this method took large numbers of immature sturgeon (Vladykov, 1964). Some problems however may be intractable such as local consumption of immature fish rather than release or registration in catches. This lack of registration prevents adequate assessment of the catch and effective management suffers (Vladykov, 1964). Iran has recently taken a number of steps to protect the caviar resources including a reduction in the annual catch from 3000 tons (sic, probably tonnes) to 1500 tons, restricting export to the government rather than private companies, combating the illegal caviar trade, and the setting of export quotas and price controls for Caspian Sea countries (Abzeeyan, Tehran, 4(5):VI; 4(7):VI, 1993). Gill netting was prohibited in 1995 (Abzeeyan, Tehran, 6(5, 6):IV-V, 1995). The break-up of the Soviet Union led to smuggling and overfishing in the newly independent countries around the Caspian but Iran was able to stabilize world prices by reducing its caviar exports by 30%. Until 1992 Russian caviar dominated the world market but more recently Iran became the main supplier with income for 1989-1994 twice that of 1979 and 1989 (Abzeeyan, Tehran 5(1 & 2):VII, 1994; Ferguson, 1994). Nevertheless, some authorities believe overfishing by the five Caspian nations, particularly in the sea where immature fish are taken along with adults, will result in the extinction of the sturgeon species there (Los Angeles Times, Part A, page 1, 28 August 1993). An account of the caviar black market in Dagestan is given by Chenciner (1998).

Moghim et al. (no date) note that juveniles of this species are caught in the beach seine fishery for other species in Mazandaran. During 2001-2002, 23,760 seine hauls had a by-catch of 2% for this species among sturgeons captured.

Lelek (1987) and Maitland (1991) report this species as "vulnerable" in Europe because it grows and matures slowly, it is exploited, affected by pollution and killed by river engineering. Critically endangered in Turkey (Fricke et al., 2007). This species showed the greatest decline among Iranian sturgeon species through overfishing of younger age groups and habitat alterations (RaLonde and Walczak, 1970b). Kiabi et al. (1999) consider this species to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, medium numbers, habitat destruction, medium range (25-75% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin. IUCN ranks all stocks as endangered (Vecsei, 2001).

Further work

The main concern with all sturgeon species is maintaining a viable commercial stock. Poaching has caused a decline in the available number of fish which can be used for breeding and moreover more than 30% of breeders do not respond to hormone stimulation (Kokoza et al., 1995). There were 6 times more nets in Azerbaijan waters and 4 times more in the Volga River delta in 1993 than in the 1980s. The legal catch will probably have to be completely prohibited (Ivanov et al., 1995). Efron (1993), for example, describes the "caviar crisis" in the Caspian Sea but problems have long been evident (Anonymous, 1961a). In 1996, 1 t of caviar was seized from smugglers in Gilan and one smuggler was fined 20 billion rials (IRNA, 28 July 1997, www.netiran.com). Maintenance of the stock may only be possible by hatchery production as river regeneration is no longer feasible because of dams. Mortality in Iran for hatchery reared eggs of 2 months age was 30-35%, for larvae 20-40%, and for fingerlings 30-40%, a satisfactory level but this could always be improved on (Petr, 1987). Yearly production of sturgeon fingerlings in government hatcheries in Iran was 1.03 millions in 1983, 1.11 in 1984, 1.13 in 1985, 2.28 in 1986, 3.10 in 1987, 3.16 in 1988, 3.15 in 1989, 4.34 in 1990, 6.60 in 1991, and 3.20 in 1992 (Emadi, 1993a). The 1996 hatchery production of sturgeon was 12.5 million in 1996 (Bartley and Rana, 1998a). A hatchery facility in Gilan covers 136 ha, produces up to 7 million sturgeon fingerlings a year with plans for up to 20 millions, and is said to be the largest and most modern sturgeon hatchery in the world.

The Israelis farm osetra and caviar from this species was on sale at Philadelphia airport at US$75/oz on 19 April 2006.

A detailed comparative study of the morphology of this species and Acipenser persicus in Iran would enable the young and adults to be clearly distinguished as well as stocks within each species as a management tool.

Sources

See under the family account.

Iranian material: Hatchery adults examined at Bandar-e Anzali.

Acipenser nudiventris
Lovetzky, 1828

Common names

شيپ (= ship, ep or sheap), تاس ماهي (= tas mahi, included under this name with A. gueldenstaedtii and A. persicus when eggs are large for fisheries statistics), tass mahi shekam brahne, سگ ماهي (sag mahi), ماهي خاويار (= mahi-ye kaviar, meaning caviar fish), keshdi, shenavar.

[kalamo, kelemo or kulamo, xazar kalamosu, gaya baligi, girt, ag-gyal or bich-nyarya in Azerbaijanian; sip or bekre balyk in Turkmenian; spiny sturgeon, thorn sturgeon, fringebarbel sturgeon, barbel sturgeon, bastard sturgeon].

Systematics

Acipenser nudiventris was originally described from the Aral Sea.

Acipenser schypa Eichwald, 1831 is a synonym. It is credited to Linnaeus by Eichwald but not described by Linnaeus; if this name is available then it is preoccupied by Acipenser schypa Gueldenstaedt, 1772 (Eschmeyer et al., 1996). Note that Holčk (1989) gives the spelling as shypa. Acipenser shipa Lovetsky, 1834 and Acipenser schypa Kessler, 1856 are synonyms. Acipenser schip Eichwald, 1841 is presumably a misspelling. Acipenser shyp Forster, 1767 may have priority but this has not been investigated.

Acipenser nudiventris derjavini Borzenko, 1950 was described as the Caspian Sea subspecies, as the type locality for the nominate subspecies is the Aral Sea, but derjavini is no longer recognised (Holčk, 1989).

A hybrid with Acipenser stellatus is reported from the Safid River (Nedoshivin and Iljin, 1927) and it also hybridises with Huso huso (Berg, 1948-1949).

V. D. Vladykov points out (in litt., 1973) that ship (in Russian) is probably a Turko-Tartar word referring to a hybrid since this species has a snout intermediate in length between that of Acipenser gueldenstaedtii, which is short, and that of Acipenser stellatus, which is long. The Russian word means prickle or thorn and has given rise to the common names for this fish in English of "spiny" or "thorn" sturgeon. Acipenser nudiventris, as its name indicates, has weakly developed or worn ventral scutes so the names spiny or thorn sturgeon are inappropriate. Vladykov recommends "sheap" as the common name to avoid confusion with the word "ship" in Russian (or for that matter in English).

Nucleotide diversity is much lower than other sturgeons in the Caspian Sea, possibly due to a smaller population size. Haplotypes of sturgeons from the Ural River in the north Caspian and Iranian waters were significantly different (Qasemi et al., 2006). Microsatellite studies indicate that there is more than one population in the south Caspian Sea and these populations are different from the Ural River one in the north Caspian Sea (Safari et al., 2007; 2008; 2008).

Key characters

This species has a continuous and thick lower lip, usually more than 50 scutes laterally, fimbriate barbels, and a transverse mouth.

Morphology

The body is deepest at the first dorsal scute. The rostrum is rounded and conical in shape in adults, more spatulate in young. Adults are covered with minute scutes giving a sandpaper texture although visually appearing smooth. Dorsal fin rays 39-57 and anal fin rays 23-37. Dorsal scutes 11-17, lateral scutes 49-74 and ventral scutes 10-17. There are no large plates on the body between the scutes. Scutes lack a hook and even juveniles have this usual feature barely developed. Ventral scutes are lost or absorbed in large adults (hence the scientific name). Gill rakers 24-45. Chromosome number is 2n=116 4, 2n=118 2,2n=118 3 (Klinkhardt et al., 1995; Nowruzfashkhami et al., 2000; Havelka et al., 2011). Nourouz Fashkhami et al. (2009) gives details of a method to produce the most metaphase plates.

Sexual dimorphism

Females are larger than males. Abdurakhmanov (1962) reports a greater average number of gill rakers in females, a longer postorbital distance in females, and longer caudal peduncle, pectoral fin, pelvic fin, snout, eye and snout tip to barbel distance in males.

Colour

The back is olive-green, grey-green or grey-blue, fading to a yellowish-white belly. Fins are grey.Juveniles mayhave the same colouration as adults or be almost black dorsally and laterally with a white belly.

Size

Attains 2.21 m and 127 kg. Safid River fish reached 43 kg, weighed when frozen, with the average being 20.1 kg, in 1914-1915 (Nedoshivin and Iljin, 1927).

Distribution

Found in the Black, Caspian and Aral seas and their drainages but extinct in the latter. In the Caspian Sea it is most common in the south, being rare in the Volga River for example. A long residency in fresh water probably accounts for their scarcity since mortality from winter and predators is high. Migrations in the Kura River extended 650 km and in the Aras River 300 km until the Mingechaur Dam was built. Enters the Aras, Astara, Safid, Tajen and Babol rivers in Iran (Derzhavin, 1934; Armantrout, 1980; CITES website, downloaded 5 April 2004). Also reported from Hasan Kiadeh by Derzhavin (1934) and by V. D. Vladykov based on field work notes made in 1962. Rostami (1961) also records this species from several localities on the Safid River. More recent works only report it from the Safid River, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea (Kiabi et al., 1999; Abdoli and Naderi, 2009) and from the Safid River (Abbasi et al., 1999). Vecsei et al. (2002) consider it as rarely observed in Iran,

Zoogeography

Presumably a relict of the past isolation of the Aral-Caspian-Black seas from the Mediterranean-Atlantic. This species is reported from the Karakum Canal and Kopetdag Reservoir in Turkmenistan by Shakirova and Sukhanova (1994) and Sal'nikov (1995) and may eventually reach the Tedzhen (= Hari) River basin of Iran.

Habitat

A rare species in trawl catches but known from feeding grounds along the eastern coast of the south Caspian Sea (Legeza, 1973). Only 100 fish enter the Kura and the Ural stock, an undammed river, is in the low thousands (Vecsei et al., 2002). This species was never as abundant as other sturgeons because young spent 2-8 years in fresh water where predators abound and food is more limited (Vecsei et al., 2002) As an adult, it favours the areas near river mouths with muddy bottoms. Markarova et al. (1991) state that its main abundance is south of the mouth of the Kura River and that it ascends the Safid Rud to spawn, although in smaller numbers than the Kura River. This species is uncommon in Iranian waters, only 2.5% in numbers and 4% in weight of the Safid River catch in 1914-1915 (Nedoshivin and Iljin, 1927; RaLonde, 1970b), and catches in Azerbaijan are not more than 5% of all sturgeons (Markarova and Alekperov, 1989). It is usually found over mud near shore at 30-60 m.

Age and growth

Maturity is attained 6-13 years in males and begins at 12-22 years in females and most are mature at 14 years. Females grow faster than males. Caspian fish grow faster and larger than those in the Aral Sea. The oldest fish in the Kura River was 35 years (Markarova et al., 1991), and maximum age is 36 years. Growth is rapid with one-year-olds in the Caspian being 23-29 cm long and weighing 40-60 g.

Food

Markarova et al. (1991) found sheap in the south Caspian Sea to eat fishes such as Atherina, Neogobius (presumably including related genera), Benthophilus and Clupeonella, polychaete worms (Nereis), and various crustaceans. Molluscs play a small part in their diet but eggs of other sturgeons and the crab Rhithropanopeus harrisii are very important. The crab, an accidental introduction to the Caspian Sea at the end of the 1950s, comprises 70% by weight of the food taken. Young sheap in the Kura River feed on insect larvae such as caddisflies, dragonflies, mayflies and stoneflies. Hashemyan et al. (2005) found diet in A. persicus, A. stellatus and A. nudiventris in coastal waters of Mazandaran and Golestan at depths less than 20 m to consist of annelids (50.8%), amphipods (41.5%), small fish 4.8%), decapods (2%) and bivalves (0.9%). Fish shorter than 40 cm fed mostly on shrimps, polychaetes and gammarids, 41-80 cm fish fed on shrimps, gammarids, polychaetes, bivalves and smaller fish, while fish greater than 80 cm fed mostly on shrimps and smaller fish.

Reproduction

A spawning migration to rivers occurs year-round but peaks in March-April and in October-December in the Kura River of Azerbaijan (Markarova et al., 1991). The spring run begins at 6.2-13.0C while the fall run is at 12.0-17.9C. Males predominate over females by 3-6 times. Spawning occurs in April-May at water temperatures of 10-25C and normal development occurs between 11.0 and 17.1C. Eggs are laid on pebbly substrates at current speeds of 1-2 m/sec. Fecundity in sea-caught fish was up to 959,100 eggs (Markarova et al., 1991). Elsewhere egg numbers may reach 1,290,000 with diameters up to 3 mm. Fry soon migrate to the sea. Spawning by individuals is not an annual event but occurs at intervals of 2-3 years for females and 1-2 years for males, allowing for recovery and fattening. Some spent fish may remain in the Kura River for up to 8 years. Halajian et al. (2007) used biopsies to determine sex and sexual maturity stages in 5 and 6 year old fish. Males matured sooner than females. Shalouei and Imanpour (2009) found that spermatozoa were immotile in ovarian fluid because of the high concentration of potassium and osmotic pressure.

Parasites and predators

Niak et al. (1970) report infestations of the ciliate Trichodina sp. in sturgeons (species unspecified) in breeding ponds in Iran. Mokhayer and Anwar (1973) report on parasites of sturgeons including this species (see under Acipenser gueldenstaedtii). Mokhayer (1976b) reports gas bubble disease in Iranian sturgeons without specifying the species of sturgeon as well as the monogenetic trematodes Diclobothrium armatum and Nitzschia sturionis. Sattari et al. (2002) record Cucullanus sphaerocephalus, Eustrongylides excisus, Skrjabinopsolus semiarmatus, Leptorhynchoides plagicephalus and Eubothrium acipenserinum, the fauna being similar to other sturgeons because of their piscivorous feeding. Sattari and Mokhayer (2005a; 2005b) recorded the occurrence of parasites in this species from the Iranian southwestern and central coast of the Caspian Sea. The species found were the nematodes Cucullanus sphaerocephalus and Eustrongyloides excisus, the cestode Eubothrium acipenserinum, the acanthocephalan Leptorhynchoides plagicephalus, and the digenean trematode Skrjabinopsolus semiarmatus. General conclusions were that the diversity of parasites was less in Iranian waters than in the northern Caspian Sea, perhaps a reflection of the more varied habitat, its productivity and the carbonate ions differing between the two regions. The diversity of parasite seems to have declined over time also, perhaps as a result of unfavourable environmental conditions, particularly in the freshwater ecosystem which limits the waters available for spawning and parasite acquisition. Shenavar Masouleh et al. (2006) found hatchery fingerlings to harbour Trichodina sp.

Economic importance

The relative scarcity of this species accounts for it being not more than 1% of the Caspian Sea catch of sturgeons. The highest catch in the Kura River seems to have been 6000 fish in the 1930s. The Iranian catch after the CITES website (downloaded 5 April 2004) was:-

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Tonnes 1.9 22.4 19.0 17.5 17.3 15.7 16.6 13.5 19.4 21.0 3.5 (spring only)

Moghim (2004b) records the total Iranian catch as 2% of the total sturgeon composition and it is declining. In 1972 the catch per unit effort was 67 tonnes and 0.5 kg/boat/day but by 2002 it was 15 t and0.09 kg/boat/day.

Conservation

Reduction in flow of the Kura River, the main spawning ground, is four times less than before regulation (5.5 km3/year compared to 20-24 km3/year). Sheap find it difficult to enter the river. Artificial propagation will be the only way to maintain the population. Between 2.9 and 6.2 million young sturgeon were released annually in the Caspian Sea from 1966 to 1971. This situation is mirrored in Iranian rivers such as the Safid Rud. This species is also particularly sensitive to oil pollution when young. There are reports that all but the Ural River population are on the verge of extinction (The Sturgeon Quarterly, 2(2):1, 1994; Vecsei, 2001). It is already extinct in the Aral Sea (DeSalle and Birstein, 1996). This species is protected in Iran since populations along the southern Caspian shore have been greatly reduced and there are not enough mature fish for fish farming (Bartley and Rana, 1998b; Vecsei et al., 2002). However the CITES website (downloaded 5 April 2004, but citing September 2000 data) reports that Iranian hatcheries still obtain some breeders from rivers. CITES also notes that the number of fishing stations for this species in Iran has been decreased by half, use of gillnets for Rutilus spp. prohibited as they take sturgeons too, egg removal by caesarian section instituted, release of fry from a breeding stock of 3000 fish, and lower export quotas instituted.

Abdolhay and Tahori (2006) give fingerling production as:-

Process/Year 2000 2001 2002 2003 2004
Female broodstock captured 15 38 16 50 25
Injected broodstock 14 21 29 32 19
Spawning rate * (%) 86 95.2 78 74 75
Fertilisation rate (%) 80 71.5 73 70 72
Survival rate in incubators (%) 54 61.5 51 49 74
Survival rate in tanks (%) 70 74.7 76 61 66
Stocking density in ponds (fish/ha) 92,100 77,005 56,194 87,986 61,667
Survival rate in ponds (%) 71 60 85 34 20
Fingerling production (x 1000) 1143 1782 1819 1414 1311

* Rate of response to hormone injection

Moghim et al. (no date) note that juveniles of this species are caught in the beach seine fishery for other species in Mazandaran. During 2001-2002, 23,760 seine hauls had a by-catch of 1% for this species among sturgeons captured.

This species is sensitive to pesticides such as diazinon. The LC50 (96 h) was 4.6 mg/l and lowered erythrocyte and lymphocyte counts were recorded with a significant increase in neutrophil counts (Khoshbavar Rostami and Soltani, 2005). Parand Avar et al. (2008) studied the effects of photoperiod during feeding by juveniles on Daphnia. Uptake was higher in dark conditions. Shalouei et al. (2009) studied extenders of spermatozoa motility and Shalouei et al. (2008) the correlation between seminal plasma indices and spermatozoa motility..

Maitland (1991) lists this species as "endangered" in Europe because of the declining population, slowness in growth and maturity, exploitation, and pollution and dams on the spawning migration. Birstein (1993) and the CITES website (downloaded 5 April 2004) also consider it be endangered. Critically endangered in Turkey (Fricke et al., 2007). Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaculture and as food.

Kiabi et al. (1999) and Moghim (2004b) consider this species to be critically endangered in the south Caspian Sea basin according to IUCN criteria while the IUCN gives endangered (Vecsei et al. (2002). Criteria include commercial fishing, few in numbers, habitat destruction, limited range (less than 25% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin.

See also under A. gueldenstaedtii.

Further work

See under A. gueldenstaedtii.

Sources

See under the family account.

Iranian material: None.

Comparative material: BM(NH) 1879.11.14:56, 1, 255.0 mm total length, U.S.S.R., Tschinas (no other locality data); BM(NH) 1879.11.14:57, 1, 217.0 mm total length, U.S.S.R., Tschinas (no other locality data); BM(NH) 1897.1.25:9, 1, 411.7 mm total length, Romania, Orsova, lower Danube (no other locality data).

Acipenser persicus
Borodin, 1897

Common name

قره برون (= qara burun, kara burun, kareh burun or ghareburun, meaning black nose), تاس ماهي (= tas mahi, this term includes A. gueldenstaedtii), دراكول (= darakul), تيريج (= tirij), تاس ماهي ايراني (= tasmahi-ye Iran), تاس ماهي ايراني (= tasmahi Irani or tasmahi-e-Iran), سگ ماهي (sag mahi), ماهي خاويار (= mahi-ye kaviar, meaning caviar fish), cetra.

[nara, nyarya or njara, neresi, Kur narasi for natio kurensis, or bekra in Azerbaijan; perseya, gunorta perseya, bekre balygy in Turkmenian; kurinskii or persidskii osetr, i.e. Kura or Persian sturgeon in Russian].

Systematics

The type locality of this species is the Ural and Kura rivers.

Regarded as not distinct from or a subspecies of Acipenser gueldenstaedtii by some authors (see Borodin, 1926; Berg, 1948-1949; Whitehead et al., 1984-1986; Keyvanfar et al., 1987; Keyvanfar, 1988; Ruban et al., 2008, 2011) but Luk'yanenko et al. (1974), Artyukhin and Zarkua (1986), Vlasenko, Pavlov and Vasil'ev in Holčk (1989), Keyvanfar and Nasrichari (1999), Pourkazemi et al. (2000), Subbotkin and Subbotkina (2001), Ghorbani and Hajimoradloo (2002), and Gharei et al. (2005) restore it to a full species on meristic, morphological, ecological, caviar proteins, serum proteins, mtDNA, genomic DNA and immunological grounds. And again, Birstein et al. (2005) consider it not to be distinct from Acipenser gueldenstaedtii on the basis of molecular analyses. Ruban et al. (2008, 2011) used meristic, morphometric and molecular data to come to the same conclusion. Acipenser gueldenstaedtii has a complex intraspecies structure according to Birstein et al. (2005) and, depending on the rivers and populations sampled for any given studies, conflicting results can arise. For the moment, the taxon A. persicus is retained here as distinct until further resolution of the problem is attained, although given the decimation of populations this may not be possible.

Moghim et al. (2009) report at least 18 groups that segregate spatially and temporally for spawning in the Caspian Sea basin. Khoshkholgh et al. (2011) using mitochondrial DNA found the that the Safid River population was reproductively isolated. Differences between other populations (Astara, Nowshahr, Bandar-e Torkoman) were not significant and most variation occurred within populations. Electrophoretic studies of blood proteins coupled with morphological data indicate that Gorgan and Safid River populations are two geographical races (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 42, 1996). Chakmehdouz Ghasemi et al. (2010, 2011) using microsatellite markers found no differences between Safid and Gorgan River populations for average number of alleles per locus and for observed heterozygosities although genetic difference was significant, warranting separate restocking efforts and conservation of gene pools.

The type subspecies is found in the Caspian Sea and Acipenser persicus colchicus Marti, 1940 in the eastern Black Sea. A natio kurensis Belyaeff, 1932 is reported from the Kur River of Azerbaijan within Acipenser gueldenstaedtii persicus.

Hybrids with Acipenser gueldenstaedtii are reported from the Volga and the Caspian Sea and have been produced artificially (Vasil'eva et al., 2001).

Two syntypes of Acipenser persicus are possibly in the Zoological Institute, St. Petersburg (ZISP, formerly ZIL) (Eschmeyer et al., 1996).

Key characters

This species has long been confused with A. gueldenstaedtii, but can be distinguished by a more elongate, massive and downward curved snout, a white belly and a grey-blue back. A drawing in Vlasenko, Pavlov and Vasil'ev in Holčk (1989) of the two species has a snout length in head length of 3.2 as opposed to 4.3 for Acipenser gueldenstaedtii but figures of snout length in total length overlap for the two species. The interorbital distance is much less in the Persian sturgeon (29.2-30.5% of head length) than in A. gueldenstaedtii (Artyukhin and Zarkua, 1986) but in small specimens examined by me from Iran, some had gueldenstaedtii interorbital distance and persicus snout length.

Morphology

The Persian sturgeon is slender with an elongate and cylindrical body, a long head, and a narrow, medium length (5.6% of total length), massive and usually depressed snout. The snout width near the mouth is 37% of head length. The pectoral fins are relatively small and have only a weak bony ray. There are usually 1-4 rows of smaller, longitudinally arranged, bony plaques between the scutes of the dorsal and lateral rows and sometimes between the lateral and abdominal rows. The barbels are located relatively closer to the snout tip than those of A. gueldenstaedtii. Sheibani and Adib Moradi (2000) described the histology of the pylorus and pyloric caecum in this species and Sheibani and Pahlavan (2003) the developmental histology of the liver and pancreas from fry to fingerling.

Dorsal fin rays 27-51, anal fin rays 16-35 according to Holčk (1989) and 30-49 and 18-32 according to Berg (1948-1949) for Kura River fish. Gill rakers 15-36. Dorsal scutes 7-19, lateral scutes 23-50 and ventral scutes 7-13 according to Holčk (1989) while Berg (1948-1949) gives 5-13, 21-42, and 7-14 respectively for scutes from Kura River fish. Safid River fish have a higher number of lateral scutes than fish from the Kura River.

The chromosome number is 2n>200 (Nowruz Fashkhami, 1996), later amended to 2n=258 4 (Nowruzfashkhami et al., 2000; Havelka et al., 2011).

Sexual dimorphism

Females are heavier and longer than males of the same age.

Colour

The back is greyish-blue to dark blue, the flanks with a steel-blue sheen, the head is lighter than the back, and scutes are lighter in colour than the background, usually pale yellow in adults but copper-gold in young. The belly is off-white, sometimes slightly yellowish.

Size

Reaches 2.42 m, possibly 2.50 m, and 76 kg, possibly 80 kg (Machacek (1983-2012), downloaded 27 July 2012). A specimen caught by the Bandar-e Torkeman fishery weighed 63 kg, as opposed to the usual weight of 18-20 kg (Abzeeyan, Tehran, 5(3 & 4):V-VI, 1994). Males migrating into the Volga River typically weigh 20-30 kg and females 30-35 kg (Vecsei and Artyukhin, 2001).

Distribution

Found in the Caspian Sea, migrating to the north but mainly in the south in the Kura River of Azerbaijan and rivers of Iran where it is more common than A. gueldenstaedtii (Ivanov and Katunin, 2001). Also in the eastern Black Sea as a distinct subspecies.

In Iran, it is found from the Astara River in the west to the Gorgan River in the east (Armantrout, 1980), but apparently not the Atrak River on the border with Turkmenistan (Berg, 1936). Distribution includes the Safid River (to Kisom and "Musachayu"), Shalman, Golchan, Langerud, "Djef", "Youssefabad", "Tchontchenan", Dehkah, "Polrud", Sorkhrud, Feridounkenar, Talar, Tajan, Neka, "Palarud", Babol, "Mirerud", and "Ferikhabad" (Kozhin, 1957; Rostami, 1961; Armantrout, 1980). Also reported from Kargan, Kopurchal, Golshan, Larim, Nirroud, Tazeabad, 12 Bahman, Nevissi, Iz Deh, and Hasan Kiadeh by V. D. Vladykov based on field work notes made in 1962. Reported more recently as occurring in the Gorgan, Babol and Aras rivers by Holčk (1989), in the Gorgan, Gharasu, Tajan, Babol, Haraz, and Safid rivers, Gorgan Bay, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea by Kiabi et al. (1999) and Abdoli and Naderi (2009) and in the Safid River and Anzali Talab by Abbasi et al. (1999). It used to ascend the Aras River but numbers in Iranian reaches were always small. Some literature records of A. gueldenstaedtii may be this species.

Zoogeography

Presumably a relict of the past isolation of the Black-Caspian seas from the Mediterranean-Atlantic.

Habitat

This species predominately inhabits the southern part of the Caspian Sea but does not form dense concentrations. Catches do not exceed 10-20 fish in 30 minutes of trawling. In winter to spring it is concentrated in the eastern coastal region and moves north in summer. In spring, maturing fish are concentrated in the southwest (Legeza, 1973). There is no seasonal variation in depth distribution in the south Caspian Sea in contrast to the middle Caspian. It is found on silty bottoms in the south Caspian Sea, sometimes with a sand admixture, at a temperature range of 4.1-28.0C and a salinity range in the sea of 8.59-14.2. This species is more stenohaline than the others, preferring waters with higher salinity as in typical marine Caspian water and is also more sensitive to lowered oxygen levels (Legeza, 1972). Kazemi et al. (2003) found that osmoregulatory ability and development of chloride cells increased during growth, enabling the fish to transition between fresh and more saline waters. Khodabandeh et al. (2007) found fry transferred from fresh water to 7.5 and 10 sea water experienced 100% mortality after one hour acclimation; cortisol treatment increased the ability of fry to withstand these salinities. Ivanov and Katunin (2001) in a trawl survey along the Iranian coast found 14.2 fish/trawl in the west and 6.7 fish/trawl in the east with undersized and juvenile fish in the west at 57 fish/trawl. The higher western catches were attributed to the presence of more rivers, in particular the Safid River. The general abundance of this species was 8.775 million fish.

This species prefers fast rivers for spawning and migrate long distances. In the Volga River they migrate at an average speed of 22.6 km/day. They may remain in fresh water after spawning for a year or more although most return to the sea. These freshwater fish overwinter in deeper holes and feed intensively on fishes, crustaceans and molluscs. Larvae move downstream immediately after hatching. Cultured fingerings can be released safely and optimally into the rivers and estuaries of Iran at an age of 33-35 days after yolk-sac absorption at a weight of 1.8-2.4 g and 6.2-7.5 cm length (I.F.R.O. Newsletter, 30-31:5, 2002).

Bahmani et al. (2001) have shown that broodfish caught by seines in the Safid River were less stressed than fish caught by gillnets in estuaries.

Age and growth

Maximum age for accidental catches in the Caspian Sea off Azerbaijan is 32 years but most (82%) are 14-23 years old. Maturity is attained between 8 and 13 years in the Kura River (Markarova and Alekperov, 1989). Most fish entering the Kura River to spawn are 7-34 years old and the main spawning population is 11-24 years. Mean lengths for Safid River fish are 161 cm for females and 141 cm for males. Females have a faster growth rate than males. Growth rate is faster than for A. gueldenstaedtii and in the Volga size and weight is considerably higher. The numbers of this species and A. gueldenstaedtii in the southern Caspian are about equal. Maximum life span is 48 years. Studies in 2007, however, when 50 stations were sampled in waters less than 10 m deep, found this species to comprise 82.7% of the absolute frequency and 59% of the biomass of the total sturgeon catch. A. gueldenstaedtii was last with 5.5% and 2.3% respectively (Iranian Fisheries Research Organization Newsletter, 51:2, 2007).

Von Bertalanffy growth parameters in Iranian females are L = 225 cm and K = 0.066 or 207 cm and 0.079 and for males 197 cm and 0.084 or 186 cm and 0.105 depending on the methodology used. Total mortality (Z) was 0.24-0.57 for females and 0.40-1.1 for males, natural mortality (M) was 0.04 for females and 0.06 for males, fishing mortality (F) was 0.47 for females and 0.34 for males, and optimum fishing mortality was (F) 0.16 for females and 0.34 for males (Iranian Fisheries Research and Training Organization Newsletter, 16:4-5, 1997). A sample of 31 males and 49 females from the Turkman Sturgeon Fishery Station in 2001 showed sexual maturity at more than 19 years for females and more than 17 years for males (Alavi et al., 2005). Fish taken at 9 fishing stations along the Iranian coast numbering 4689 individuals had a mean length of 139.1 cm for males and 153.4 cm for females, weights 19.95 kg and 29.09 kg respectively and an age of 14.15 years and 16.59 years respectively. The sex ratio was 1:2.2 in favour of females and the majority of females (89.6%) were at level IV maturity. An increase in sexual maturity of females occurred in autumn while males were most mature from June to September (Falahatkar, 2006). Samples taken from the whole Caspian shore of Iran from 2002 to 2004 numbering 11,480 fish had a length range of 90-240 cm and growth parameters L∞ = 230 cm and K = 0.058 year-1 (www.shilat.com, downloaded 28 February 2007). Bakhshalizadeh et al. (2011) collected data from commercial Iranian fisheries (2008-2010) and found a maximum age of 39 years, growth parameters for females were L = 173.07 cm, K = 0.1 year-1 and Z = 0.45 year-1 and for males 164.33 cm, 0.08 year-1 and 0.76 year-1. Differences between this and previous studies were attributed to increased fishing and environmental degradation.

Food

Diet is composed of molluscs, crustaceans including the introduced crab (Rhithropanopeus harrisii), worms, chironomids and fish such as gobies (Gobiidae) and small herrings (Clupeonella spp.). Fish are a large part of the food of young sturgeon at sea. Azari Takami et al. (1980) found adults to prefer fish, mostly gobies, followed by crustaceans and two clam species Abra ovata and Cerastoderma umbonatum in Iran. The zebra mussel is also eaten as evidenced by a mass of these small clams from the stomach of a 1.6 m, 35 kg female from Nevissi caught on 29 September 1962. Reportedly the food diversity of this species is much less than for Huso huso and Acipenser gueldenstaedtii. Commercial sized fish feed particularly in the northern Caspian Sea (Ivanov and Katunin, 2001). Hashemyan et al. (2005) found diet in A. persicus, A. stellatus and A. nudiventris in coastal waters of Mazandaran and Golestan at depths less than 20 m to consist of annelids (50.8%), amphipods (41.5%), small fish 4.8%), decapods (2%) and bivalves (0.9%). Fish shorter than 40 cm fed mostly on shrimps, polychaetes and gammarids, 41-80 cm fish fed on shrimps, gammarids, polychaetes, bivalves and smaller fish, while fish greater than 80 cm fed mostly on shrimps and smaller fish. Immature A. persicus, less than two years old, from fishing stations off Gilan fed on the benthic invertebrates, namely the polychaetes Hypania sp., Hypaniola sp. and Nereis sp., the cumaceans Pterocuma sp. and Stenocuma sp., the clam Abra ovata, and the crustaceans Paramysis sp. and Gammarus sp. Adults fed mostly on fish (gobies, smelts and herrings). Haddadi Moghadam et al. (2009) studied diet in fish collected in summer and winter in the south Caspian Sea from 2004 to 2006. Food items were fishes (Neogobius sp., Atherina caspia, Clupeonella cultriventris (= caspia) and invertebrates (polychaete worms such as Ampharetidae and Nereis diversicolor; crustaceans such as Gammarus and Paramysis; and the bivalve mollusc Abra ovata). The diet varied with season and size group and was similar to A. stellatus. Imanpour Namin et al. (2010) studied southern Caspian Sea fish and found the diet included Gobiidae, Mysidae, Gammaridae, Nereidae, Ampharetidae, Pseudocumidae, Clupeidae, Syngnathidae, Scorbicularidae, Cardidae and insects. Diet diversity decreased with increase in fish size, from 8 to 5 to 2 items in length classes <30 cm, 30-60 cm and >60 cm. Gobiidae dominated in the largest length class and Gobiidae and Mysidae in the middle length class.

The account under A. gueldenstaedtii above gives some comparative details of diet.

Reproduction

This species was long confused with the chalbash, A. gueldenstaedtii, and was thought to be a late spring or early summer spawning population of that species. The spawning run follows that of A. gueldensatedti. Spawning runs are dominated by the spring form and winter fish are very rare (Artyukhin and Zarkua, 1986). Fecundity off Azerbaijan is up to 558,900 eggs (Markarova and Alekperov, 1989) but may reach 840,000 eggs. In the Safid River it attains 375,000 eggs. The eggs are brownish-grey and measure up to 3.8 mm in diameter.

The unusually large specimen caught by the Bandar-e Torkeman fishery gave 22 kg of caviar, almost 35% of the body weight (Abzeeyan, Tehran, 5(3 & 4):V-VI, 1994).

Spawning takes place at 15-25C, mainly at 17-23C, at higher temperatures than A. gueldenstaedtii (8-18C). Spawning sites are gravel, pebble, clay or shell beds, depths are 2-20 m and current speeds 1.0-1.7 m/sec. Catches of what were probably this species in the estuary of the Safid River for the period 1928/29-1936/37 showed strong peaks in April and May with a minor peak in September and October (Vladykov, 1964). The Safid is the main spawning river in Iran (Aslaanparveez, 1993). Spawning takes place in southern Caspian rivers from April to June and again in August to September. There is a 2 month interruption in spawning in the Safid River during summer when water temperatures are 26-30C. There is a period of at least 2-4 years before this species can spawn again. Incubation takes 3-5 days. Shafizadeh and Parivar (1999) state that most embryos hatch 82-87 hours after fertilisation, most of the yolk is absorbed 6 days after hatching and swimup fry appear from day 7 to 8 at 19-21C. The timing of passage of fingerlings into the sea after a hatchery release into the Tajan River was found to be 12-72 hours after release with a peak migration at 0-3 a.m. Smaller fingerlings stayed longer in the river before leaving (Ramezani, 2003).

Egg size is positively correlated with larval length and weight, yolk sac volume, hatching time and duration of hatching time, but there was no correlation with mortality during yolk sac absorption or with mortality during the first feeding stage (Nazari et al., 2009). Imanpoor et al. (2009) found the average hydrated egg diameter was 3.64 mm, yolk diameter was 3.26 mm, surface-to-volume ratio was 1.65 and yolk sphere-to-perivitelline space ratio was 0.75, the latter two being very high. The metabolic rate was low and spawning can occur in low-temperature waters.

Asadi et al. (2006) have examined serum biochemical parameters that can be used assessing maturity and managing endangered species.

Parasites and predators

Mokhayer (1976b) reports gas bubble disease in Iranian sturgeons without specifying the species of sturgeon as well as the monogenetic trematodes Diclobothrium armatum and Nitzschia sturionis. Most of the data for parasites and diseases summarised under A. gueldenstaedtii above for Iran may well refer to this species. Soltani et al. (2000) examined parasites of this species in three locations in Gilan and found Cucullanus sphaerocephalus and Skrjabinopsolus semiarmatus had the highest prevalence and intensity. Eustrongylides excisus, Anisakis sp. and Amphilina foliacea were recorded for the first time from this sturgeon and diet was strongly correlated with diversity of parasites. Soltani and Kolbassi (2001) describe the use of different antigens for fingerlings against Aeromonas hydrophila septicaemia. Hajimoradloo (2002) records the nematode Cystoopsis acipenseris in juveniles at a frequency of 5.83%. Hajimoradloo and Ghorbani Nasrabadi (2003) found the prevalence of metazoan parasites in juveniles of this fish in the southeast Caspian Sea to be 10 species with Anisakis larvae the highest at 19.7%. Pazooki and Masoumian (2004) report on blood parasites form fish caught at Anzali, recording Cryptobia acipenseris and Haemogregarina acipenseris. These parasites caused no pathological effects in the wild fish but can lead to severe infections and cause anaemia on fish farms. Gorogi (2006a) recorded the nematode Cucullanus sphaerocephalus, the the digenean Skrjabinopsolus semiarmatus and the acanthocephalan Leptorhynchoides plagicephalus from Iranian waters. Sattari and Mokhayer (2005a; 2005b) recorded the occurrence of parasites in this species from the Iranian southwestern and central coast of the Caspian Sea. The species found were the nematodes Cucullanus sphaerocephalus, Eustrongyloides excisus and Anisakis sp., the cestode Amphilina foliacea, the acanthocephalan Leptorhynchoides plagicephalus, the digenean trematode Skrjabinopsolus semiarmatus, the monogenean trematodes Diclybothrium armatum and Nitzschia storionis and the crustacean Pseudotracheliastes stellatus. General conclusions were that the diversity of parasites was less in Iranian waters than in the northern Caspian Sea, perhaps a reflection of the more varied habitat, its productivity and the carbonate ions differing between the two regions. The diversity of parasite seems to have declined over time also, perhaps as a result of unfavourable environmental conditions, particularly in the freshwater ecosystem which limits the waters available for spawning and parasite acquisition. Shenavar Masouleh et al. (2006) found hatchery fingerlings to harbour Diplostomum spathaceum, Trichodina sp. and Gyrodactylus sp. Ebrahimi and Malek (2007) found the helminths Cucullanus sphaerocephalus, Skrjabinopsolus semiarmatus, Leptorhynchoides plagicephalus and Eustrongylides excisus. Haghparast et al. (2007) found Cucullanus sphaerocephalus and Skrjabinopsolus semiarmatus to have the highest incidence (80 and 55%) in digestive tracts of broodstocks. Masoumzadeh et al. (2007) examined broodstocks and found Cucullanus sphaerocephalus, Skrjabinopsolus semiarmatus, Eubothrium acipenserinum, Corynosoma strumosum, Leptorhynchoides plagicephalus and Amphilina foliacea. Rajabpour et al. (2008) recorded helminth parasites from fish at three coastal stations in the southeast Caspian Sea, namely the nematode Cucullanus sphaerocephalus and the digenean Skrjabinopsolus semiarmatus. Jalilpour et al. (2009) identified a wide range of fungi on eggs and larvae of fish from the Shahid Beheshti Sturgeon Rearing Centre. Bazari Moghaddam et al. (2010) examined larvae and fingerlings in the Shahid Beheshti Hatchery and observed development of parasitism from the ciliate Trichodina reticulata and the digenean trematode Diplostomum spathaceum after release into earthen ponds and the river respectively.

Economic importance

See also under A. gueldenstaedtii where much of the data on this species is subsumed. The average weight of eggs in this species in Iran is 4-6 kg per fish and these eggs are ideal for first grade caviar (Vladykov, 1964). This species has the largest abundance (61.9%), biomass (50%) and catch-per-unit-effort among all Acipenseridae in Iran in both 2003 and 2004 from sampling 85 stations at 2-100 m depths (followed by A. stellatus (Iranian Fisheries Research Organization Newsletter, 38:1, 2004)).

Catches of A. persicus declined in the Safid River after construction of a dam at Manjil which released water for rice farming and held back sediment, both important triggers for attracting spawning sturgeon. In 1962, flow was reduced to 7-10 cu m/sec resulting in water temperatures up to 29C, destroying insects and crustaceans on which young sturgeon fed and making the river narrow and shallow (Vladykov, 1964). Many fish were attracted into the stronger flow of irrigation canals where they eventually died. Catches of this and other species also declined because of the introduction of the more efficient synthetic fibre gill nets in 1957 (Vladykov, 1964). In Iran this sturgeon is caught both in the sea and in rivers.

Catches in the Safid River in 1930/31-1934/35 peaked at 13,867 fish in April with 10,693 fish in May and 3433 fish in March and an annual total of 32,700 fish (Berg, 1948-1949). Holmes (1845) and Eastwick (1864) reported on fishing for sturgeon in the Safid River. The principal method in the first half of the nineteenth century was to stretch 100 foot (30.5 m) lines across the very shallow, rapid and murky river with 1 yard (0.9 m) lengths of line attached at intervals of about 2 feet (0.6 m). These lengths of line were armed with large hooks which snagged the migrating sturgeon. Sturgeon up to 5 feet (1.5 m) were caught from February to April. At the beginning of February about 100 fish were taken each day, rising to 600-800 at the end of the month, 800-2000 in March and to 3500-3800 per day in April. After May sturgeons had little or no roe. About 125,000 fish were taken annually and sold for their flesh, caviar and isinglass.

Keyvanfar and Nasrichari (1999) state that from an average 2000 t annual catch over 10 years (1980-1990) 25% of meat and 24% of caviar were from this species while 17% of meat and 14% of caviar were from A. gueldensatedtii. This species produces 51% of Iran's caviar production (I.F.R.O. Newsletter, 30-31:5, 2002). Catches in the Kura River from 1974-1978 varied from 90 to 220 tonnes. Salehi (2011a) summarises the stock enhancement through fingerling release over the previous two decades in Iran. For the period 2000-2004, for example, 78.7% of fingerling production were this species.

Extensive studies have been carried out on this species, either on hatchery specimens to improve their survival or using hatchery specimens as experimental organisms. These studies include rearing using earthworms (Kazerooni Monfared, 1995); ideal stocking densities in tanks (Derakhshandeh Ghazi Mahale, 1997); stress during transport and confinement of brood stock as evaluated using blood samples (Bahmani et al., 2000; Bahmani and Oryan, 2004); on growth performance using Daphnia magna and Artemia nauplii as food for fry (50% Artemia and 50% Daphnia given at 70% larval body weight was the best), and on osmoregulation during restocking (Jabbarzadeh Shiadeh et al., 2000); procedures against infectious diseases using antigens from Aeromonas hydrophila which causes septicaemia (Kalbassi et al., 2000); on effective stocking density of eggs and larvae in incubators and rearing tanks (Mohseni et al., 2000); haematological variables in juveniles and adults at different water temperatures (Pourgholam and Saeidi, 2000); on optimum feeding rate for fingerlings (Yousefpour Pirbazari et al., 2000); on blood parameters for fingerlings in a Gilan fish farm (Shahsavani et al., 2001); a histological study of the intestines (Sheibani and Pousti, 2001); sperm has been cryo-preserved to conserve the gene pool (Vecsei and Artyukhin, 2001); on clove oil having no significant difference with MS222, an anaesthetic used in fish farms (Abtahi et al., 2002; 2003); food and feeding of fingerlings after release and their travel time to the estuary (Kamali and Imanpoor, 2002); the relation between biochemical composition of eggs and their fertilisation rate (Mohammad Nazari et al., 2002); changes in the levels of sex steroids as oocytes developed (Nazari et al., 2002); nutrition in fish ponds where cladocerans and chironomids were staples and copepods and their nauplii were secondary items (Aslan Parviz and Aghaei Moghadam, 2003; Aghaei Moghadam and Aslan Parviz, 2006); the enhancement effect of ozone and physical treatment on the hatching rate of eggs (Ghomi et al., 2003); purification and partial characterisation of serum immunoglobulins (Kalbassi et al., 2003); physiological studies on the liver oxidase system (Karimzadeh et al., 2003); toxicity of the insecticide diazinon to fingerlings (Pazhand et al., 2003); dietary levels of fat and protein effecting growth and chemical composition of fingerlings (Ebrahimi et al., 2004; Mohseni et al., 2007); on sperm motility (Hadi Alavi et al., 2004); the identification of fatty acids in the flesh and the effects of long-term freezing on them (Hedayatifard and Moini, 2004); effect of temperature on fertilisation percentage achieved by broodstock (16.1-18.0C was optimal)(Hosseini Najd Gerami and Hajimoradlu, 2004); the effect of the timing of first feeding with live food on growth and survival of larvae (Kordjazi et al., 2004); determination of the 96h LC50 of Saturn, a herbicide, and Malathion, an insecticide, at 0.007 and 10 mg/l respectively (Nezami et al., 2004); histology of the gut from hatching to 56 days (Pahlavan Yali et al., 2004); levels of zinc and copper in muscle tissue and caviar (Sadeghird et al., 2004); reproductive conditions of broodstock and when they should no longer be used (Hosseini Najdegrami et al., 2005); the optimal weight and length for release of fingerlings into rivers and estuaries (1.8-2.4 g, 6.2-7.5 cm, 33-35 days after yolk sac absorption)(Kazemi et al., 2005); the timing of initial feeding in relation to behaviour (negative phototaxis and assumption of a benthic life at 5-6 days post-hatching) and expulsion of the melanin plug (larvae can feed with it present so expulsion cannot be used to determine active feeding)(Kordjazi et al., 2005); sperm density and fertilisation rate (Nazari et al., 2005); the toxic effects on fingerlings of various pollutants such as the oil products phenol and 1-naftol, the herbicide butachlor, and polyaromatic hydrocarbons from oil wells in the Caspian Sea (Nezami et al., 2005; Padjand et al., 2005; Soltani et al., 2006); a macroscopic and microscopic study of the spleen and and associated lymphatic tissue (Sheibani, 2005); evaluation of hydrogen peroxide against malachite green (possibly toxic and teratogenic) for fungal disinfection of eggs showed the former to be superior (Vahabzadeh et al., 2005); antifungal studies on eggs comparing the utility of formalin, malachite green and potassium permanganate in fish farms, the latter being safest for controlling Saprolegnia (Abtahi et al., 2005); sperm studies evaluating ionic composition and osmolality of seminal plasma, sperm density and motility in regard to sperm cryopreservation (Alavi et al., 2006); inulin-like growth factor-I inducing oocyte maturation (Bahrami Kanagar et al., 2006); the micro-cesarean method of extracting eggs from brood stock was better than conventional methods (Feyzbakhsh et al., 2006); the use of rotifers (Brachionus plicatilis) in conjunction with Artemia nauplii as food for larvae (Haddai Moghadam, 2006); use of oxolinic acid bioencapsulated in Artemia urmiana as a means to increase resistance to Aeromonas hydrophila infection in larvae (Hajimoradlou and Agh, 2006); studies on blood serum osmotic and ionic regulation in wild adults and reared juveniles, important in understanding the best use of water with different salinities in commercial rearing of this species (Kazemi et al., 2006); induction of ovulation using glycerin as a solvent for hypophysis powder proved better than physiologic serum (Noroozi et al., 2006); feeding formulated diets to larvae and juveniles in hatchery rearing (Pourali Fashtomi and Mohseni, 2006); establishing blood serum parameters as tools in disease prognosis and control (Shahsavani et al., 2006a, 2006b); the maximum allowable concentration of Safid River sediments as determined in aquaria was 1536.74 mg/l (Yosefi Garakoei et al., 2006); Abedian Kennari et al. (2007) on use of Daphnia magna enriched with cod liver oil as a source of highly unsaturated fatty acid on growth, survival, stress resistance and fatty acid composition of larvae; the effect of stripping frequency on ionic content and osmolality in seminal plasma composition (Alavi et al., 2007); details of sperm morphology in comparison to that of fil mahi (Baradaran Noveyri et al., 2007); comparison of the efficiency of the Yushchenko and Azarakhash incubators, the latter being better in terms of fertilisation percentage, mortality rate, active feeding and survival (Farabi et al., 2007); ability of Artemia urmiana to act as a carrier of oxolinic acid, a drug used to combat infection in fish larvae (Ghorbani et al., 2007); use of probiotic bacillus bioencapsulated with Artemia urmiana nauplii to increase growth of larvae (Jafarian et al., 2007); fatty acid composition in fresh and frozen tissues, concluding cold storage should not exceed 12 months (Moeini and Hedayatifard, 2007); variations in meat quality using dry and mix salting (salt and 1% madder) (Seyfzadeh et al., 2007); propagation efficiency of broodstock from two farms in Mazandaran and Golestan were shown to be different (Yousefian and Farabi, 2007); Askarian et al. (2008) examined the gastrointestinal tract for lactic acid bacteria and found the population levels to be significantly lower than in Huso huso;on amino acids in food pellets increasing consumption (Jafari Shamushaki et al., 2008); fertilising ability of cryopreserved spermatozoa (Alipour et al., 2009); on serum biochemical parameters (Asadi et al., 2009); on the median lethal concentration of suspended sediment from the Safid River, this pecies showing higher tolerance than A. stellatus (Garakouei et al., 2009); isolation of Lactobacillus species, which ferment carbohydrates, from the intestine (Ghanbari et al., 2009); changes in fatty acid composition after freezing and long-term cold storage (Hedayatifard and Keyvan, 2009); use of Artemia urmiana enriched with the essential fatty acid docosahexaenoic acid and its effects on growth, survival and composition of larvae (Hafezieh et al., 2009); the important influence of temperature on hatching time, start of exogenous feeding, growth performance and survival of larvae (Jalali et al., 2009); immunolocalisation of gill chloride cells used in ionic and osmotic regulation (Khoushnoud et al., 2009); varied effects of egg size on length, weight growth and survival of prelarval and early feeding stage (Nazari et al., 2009); recommended use of methyl paraben as a safe preservative in caviar infected with the bacterium Clostridium botulinum (Salmani et al., 2009); regulation of water temperature during the embryonic period, temperatures of 15-18C being the upper limit of thermal optima (Soleymani and Karimabadi 2009); fish effects of cooking methods on the physico-chemical and nutritional and digestibility properties of fillets (Alipour et al., 2010); identification of 13 fungal species in cultivated and natural populations (Firouzbakhsh et al., 2010); positive effects of Artemia urmiana enriched with highly unsaturated fatty acids on growth, survival and fatty acids composition of larvae (Hafezieh et al., 2010); the effects of sex steroids on hormonal control of reproduction (Hajirezaee et al., 2010); anaesthetic effects of clove essence (400 p.p.m. and 24C was best treatment and for recovery) (Imanpoor et al., 2010); the impact of plasma sex steroids on gonad development (Nazari, 2010); the successful use of the synthetic hormone LHRH-A2 on artificial propagation (Nazari et al., 2010): the relationship between steroid hormones and maternal characteristics and larvae (Nazari and Ghomi (2010); interrelationships among egg, larvae and maternal characteristics (Nazari et al., 2010); live feed effects on growth rate of fingerlings (Yousefian et al., 2010); serum biochemical parameters for disease monitoring and sublethal hatchery conditions (Yousefian et al., 2010); the growth performance, survival rate and resistance to thermal stress of Artemia nauplii bioencapsulated with ergosan (Ahmadifar et al., 2011); the increase in growth efficiency and survival rate of larvae fed Daphnia magna bioencapsulated with probiotic bacilli (Faramarzi et al., 2011); growth and changes in fatty acid levels during early larval development (Babaei et al., 2011); inhibitory effects on lipid oxidation (or rancidity) of ascorbic and citric acids compared with vacuum packaging in frozen fillets; toxicity of the herbicide glyphosate (Filizadeh and Rajabi Islami, 2011); bioencapsulated Daphnia magna with yeast product enhancing resistance against stress and disease of larvae (Lashkarbolouki et al., 2011); the effect of various feeds on growth and survival of larvae (Lashkarbolooki et al., 2011); ultrastructure and osmoregulatory function of larval kidneys (Taghizadeh Rahmat Abad et al.,  2011); on Lactobacillus species from the guts (Ghanbari and Jami, 2011b); bioencapsulated Daphnia with yeast promoted feeding parameters and growth in larvae (Jafaryan and Soltani, 2012); the effect of photoperiod on egg hatching rate with soem dark conditions being necessary (Kazemi et al., 2011); sex chromosomes were not differentiated sufficiently using AFLP to identify males and females at an early life stage (Yarmohammadi et al., 2011); use of LHRH-a to stimulate immature broodstock to mature (Amini et al., 2012); a yeast-enriched Daphnia diet increases growth and feed efficiency, and stress tolerance, in larvae under unfavourable environmental conditions (Lashkarbolouki et al., 2012); use of cytochrome P450 1A in this sturgeon as a biomarker for impact assessment of polycyclic hydrocarbons pollutants (Karimzadeh et al., 2012); the effect of starvation and re-feeding on compensatory growth performance and on insulin and blood serum values in juveniles (Yarmohammadi et al., 2012); etc.

Conservation

See also under A. gueldenstaedtii. Catches in the sea off Iran are made with large seines and gill nets and many juveniles and fish below legal size are taken. Netting of sturgeon along the coast of Iran has been banned and hatchery production in Iran is directed to this species to maintain stocks. Moghim et al. (no date) note that juveniles of this species are caught in the beach seine fishery for other species in Mazandaran. During 2001-2002, 23,760 seine hauls had a by-catch of 54% for this species among sturgeons captured. Moghiem (2003) found that catch-per-unit-effort fluctuated from 2.249 to 2.971 kg over the previous decade, mean length, weight and age declined, the age structure changed with younger fish increasing in numbers, and catches showed an increase. Alavi et al. (2005) found overfishing of females in their sample from the Turkman Sturgeon Fishery Station.

Abdolhay et al. (2006) report on 1062 adults caught in 1998 of which 581 fish were injected with hypophysis extract and produced 22.5 million fingerlings while in 2002, 802 were caught and 538 produced 12.3 million fingerlings. Yousefian et al. (2010)found that river water mixed with well water, saturated with oxygen and maintained at 180.2C were the best conditions for artificial propagation. The samples used weighed 14-52 kg and an average of 52,000 eggs per female were produced. Fertilisation was 65 and 75% in two farms, significantly different, and hatching rate was 61% in both farms. Fungal infections were a significant problem

Hormonal studies are used to select fertile broodstock to ensure effective aquaculture (Mojabi et al., 1999; Safi et al., 1999) and other studies relevant to hatchery success, and thus conservation, are listed above. Nezami et al. (2000) maintain that sea-ranching has restored this species in Iran. Moghim et al. (2001) have used ultrasonography to determine sex and maturity of this species as there are no obvious external sex characteristics. Sex and maturity determination were accurate at 100% and 98.6% respectively, confirmed by necropsy, and thus would prevent the loss of male and immature female fish if the technique were used in the caviar fisheries.

This species is now found in the northern Caspian Sea, the fish being from Iranian stocking programmes (Kottelat and Freyhof, 2007).

Amini (2005) and Abdolhay and Tahori (2006) summarise hatchery production for this species:-

Process/Year 2000 2001 2002 2003 2004
Female broodstock captured 661 591 620 2056 742
Injected broodstock 437 492 528 1288 436
Spawning rate* (%) 81 86.5 410 (sic) 80 85
Fertilisation rate (%) 72 76.1 83 71 75
Survival rate in incubators (%) 56 52.6 75 50 64
Survival rate in tanks (%) 76 76.4 53 67 74
Stocking density in ponds (fish/ha) 84,076 89,131 76,000 97,941 95,661
Survival rate in ponds (%) 56 47.4 56 52 56
Fingerling production 13,711,199 16,278,595 12,301,214 18,388,962^ 17,412,529

* Rate of response to hormone injection; ^ 18,288 in Abdolhay and Tahori (2006)

Studies on heavy metal contamination (Zn, Cu, Cd,, Pb and Hg) of both flesh and caviar showed levels were below the maxima allowed for consumption, based on international standards (Sadeghi Rad et al., 2005; Amini Ranjbar et al. (2003), Amini Ranjbar and Shariat, 2006; Sadeghi Rad et al., 2009).

Lelek (1987) lists this species as endangered. Extinct in Turkey (Fricke et al., 2007). Kiabi et al. (1999) consider this species to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Vecsei and Artyukhin (2001) list it as endangered with the IUCN. Criteria include commercial fishing, abundant in numbers, habitat destruction, widespread range (75% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin. Mostafavi (2007) lists it as vulnerable in the Talar River, Mazandaran. Kottelat and Freyhof (2007) state that there is likely no natural reproduction in Iranian waters, fish being from artificial stocking programmes.

Further work

Fresh samples of sturgeon from Iranian rivers should be examined systematically and with care to determine if they are indeed this species and not A. gueldenstaedtii. A detailed comparative study of the morphology of this species and Acipenser gueldenstaedtii in Iran would enable the young and adults to be clearly distinguished as well as stocks within each species as a management tool.

Sources

Holcik (1993) and Shariati (1994) give accounts of this species in Farsi. See also under family above.

Iranian material: Hatchery adults examined at Bandar-e Anzali.

Acipenser ruthenus
Linnaeus, 1758

Found in the Caspian Sea basin but no records from Iran proper. Single specimens have been recorded as entering the Kura River of Azerbaijan and fishermen reported one fish from off Soviet Astara in 1929 (Berg, 1948-1949) on the border with Iran. The import of 30,000 fingerlings and 20 male parent stock of this species to Iran for artificial reproduction was envisaged in an agreement with the Russian Research Centre of Commercial Sturgeon Reproduction in 1995 (Iranian Fisheries Research and Training Organization Newsletter, 9:3, 1995). Tatina et al. (2010) studied effects of dietary vitamins C and E on haematological and biochemical parameters in this fish in the breeding centre in Rasht.   Acipenser primigenius Chalikov, 1944 is a hybrid of this species and Acipenser gueldenstaedtii (Eschmeyer et al., 1996). The Farsi name is استرلياد (esterliad). Listed as Endangered in the Volga River (Peterson et al., 2009).

Acipenser stellatus
Pallas, 1771

Common names

ازون برون or اوزون بورون (uzun burun or ozoonboroon = long nose), دراكول (= derakul or darakul); tirij (after Wossugh-Zamani (1991a), meaning shaped like an arrow; see also A. persicus); سوروگا (= sevruga or sevroga), سگ ماهي (sag mahi), ماهي خاويار (= mahi-ye kaviar, meaning caviar fish), puze draz.

[uzunburun, Kur uzunburun for natio cyrensis, ag-balyk, all in Azerbaijanian; tirana in Turkmenian; sevryuga, sevruga or stellate sturgeon (this term also includes A. nudiventris with small eggs for fisheries statistics), yuzhnokaspiiskaya sevryuga or South Caspian stellate sturgeon, both in Russian; star or starred sturgeon].

Systematics

Originally described from the Volga River near Simbirsk.

Acipenser seuruga Gldenstdt, 1772 from the Caspian Sea, Acipenser hellops Pallas, 1814 from the Black and Caspian seas, Acipenser Helops Pallas, 1814 from the Araks River, and Acipenser Ratzeburgii Brandt in Brandt and Ratzeburg, 1833 from the Caspian Sea at the mouth of the Emba River, are synonyms.

Acipenser stellatus stellatus natio cyrensis Berg, 1932 is described from the southern Caspian Sea and tributary rivers but has no taxonomic status as an infrasubspecific rank. Morphologically, this Kura River form is similar to north Caspian members of the species, differing principally in postorbital distance. Growth and fecundity are lower in the Kura form and spawning time is different. M. Poorhazemi (Pourkazemi) finds that A. stellatus is highly polymorphic with more than one population using molecular techniques (Iranian Fisheries Research and Training Organization Newsletter, 14:4-5, 1996). Norouzi et al. (2009) used microsatellite markers to determine that there is more than one population in the south Caspian Sea which has importance in terms of stock management, restocking and conservation. Shabani et al. (2003; 2006) found no significant differences between Volga River and Gorgan, Tajan and Safid River fish of Iran when examining mtDNA. Norouzi et al. (2008) and Norouzi and Pourkazemi (2009) examined the population and genetic structure of this species in Iranian waters using microsatellite markers and found evidence for at least three populations, particularly a separate one in the Safid River, and probably more than one in each river such as the Safid and Gorgan rivers.

A hybrid with Acipenser nudiventris is reported from the Safid River (Nedoshivin and Iljin, 1927). Artificial hybrids with Huso huso have been produced in Mazandaran for aquaculture projects (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 6, 1996).

Key characters

This sturgeon has a long snout (59-65% of head length) with a pointed tip in contrast to the short snout and rounded tip in A. gueldenstaedtii and A. persicus. The continuous lower lip in A. nudiventris and the large crescentic mouth in Huso huso distinguish these species.

Morphology

The lower lip is interrupted at its centre, barbels are not fringed, are short, and do not reach the mouth but are closer to the mouth than the snout tip.

Dorsal fin rays 38-54 and anal fin rays 20-40; or 40-54 and 22-35 respectively in the Kura for natio cyrensis (Berg, 1948-1949). Dorsal scutes 9-16, lateral scutes 26-43 and ventral scutes 9-14. There are smaller scutes between the main rows. Gill rakers 24-29, usually 25-26 in natio cyrensis. Chromosome number 2n=115 1 (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 43, 1996), 2n=118 2 or 113 1 (Iranian Fisheries Research and Training Organization Newsletter, 8:5, 1995) or 2n=118 1 (Nowruz Fashkhami, 1996), 2n=114 (Nowruz Fashkhami and Khosroshahi, 1999); 2n=1466 (Chicca et al., 2002). Sheibani (2003a) described the anterior digestive canal of this species.

Keyvanfar (1986) found a transferrin polymorphism in the serum proteins of this species but not the other Iranian species of sturgeon and Keyvanfar (1988) found several variants corresponding to transferrin in the other species.

Sexual dimorphism

Females are larger than males of the same age; in the Ural River 1.3-1.6 times larger. Head depth and preanal distance differ between sexes in Kura River fish but only when gonads are ripening. Abdurakhmanov (1962) reports a longer anal fin, snout, and snout tip to barbel distance in males, and a longer predorsal length, preanal length, postorbital length and a greater caudal peduncle depth in females.

Colour

The back is dark grey, ash grey or cinnamon brown, almost black in some fish, and fades to a white belly. Flanks are yellowish-white. In small fish, the scutes are lighter than the adjacent body and so are distinctive. Sea fish are darker than river fish. An eyeless specimen, 1.11 m long, caught in Mazandaran was dark black (Abzeeyan, Tehran 4(7):V). The eyes were completely absent and their position on the head was covered with smooth bone.

Size

Attains about 2.21 m and possibly more than 80 kg. Sternin and Dor (1993) cite a specimen of 2.9 m. Iranian captures averaged 1.3-1.4 m and 9-10 kg in the 1950s (Farid-Pak, no date). One of the largest specimens ever caught was 2.18 m long and was taken off the Astara River on the border of Azerbaijan and Iran in 1932. Much larger fish are known from archaeological sites of the 10th-13th centuries on the Terek River, up to 2.7 m (Tsepkin and Sokolov, 1971).

Distribution

Found in the Adriatic, Aegean, Black and Caspian seas and their drainages but the largest populations are in the Caspian. Generally found from the Astara River in the west to the Gorgan River in the east in Iran (Berg, 1948-1949; Kozhin, 1957; Armantrout, 1980) but not the Atrak River on the eastern Caspian border of Iran with Turkmenistan (Berg, 1936). Found in the Safid River at Kisom and the Mirerud (Derzhavin, 1934; Kozhin, 1957). It used to ascend the Aras River but numbers in Iranian reaches were always small (Berg, 1948-1949). The Kura River catch was up to 90% of the sturgeons taken. Rostami (1961) records this species from several localities on the Safid River and from the Golchan, "Djef", Youssefabad, Tchontchenan, Dehkah, Sorkh, Talar, Tajan, and Neka rivers. Also reported from Kargan and Hasan Kiadeh by V. D. Vladykov based on field work notes made in 1962. Reported more recently from the Gorgan, Gharasu, Tajan, Babol, Haraz, and Safid rivers, Gorgan Bay, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea by Kiabi et al. (1999) and Abdoli and Naderi (2009) and from the Safid River and Anzali Talab by Abbasi et al. (1999).

Zoogeography

Presumably a relict of the past isolation of waters now encompassing the Black-Caspian seas.

Habitat

This sturgeon is found in large concentrations in the eastern coastal region of the south Caspian Sea in August-September with up to 25-30 fish taken in a single trawl, having moved south from northern waters. Ivanov and Katunin (2001) note the densest concentration in the per-estuary zone of the Gorgan River, with catches reaching 26 fish/trawl while along the central part of the Iranian coast catches did not exceed 4 fish/trawl. At the end of winter and particularly in early spring, uzun burun move onto the Iranian shore. Migrations between the Kura River lower reaches, the Safid River and elsewhere are reported. They usually does not descend below 100-130 m except along the southern shore of the Caspian Sea (Legeza, 1973) where they may descend to 300 m. Uzun burun are common only down to 50 m. There is no seasonal variation in depth distribution in the south Caspian Sea in contrast to the middle Caspian. They are often found in surface waters during the day, and retire to the bottom during the night. Uzun burun are found on silt and sand-silt bottoms but will also feed on sand and shell grounds. Temperature range is 4-24C, in winter 7.5-10.5C and 11.0-24.0C in summer and fall, with an absolute range of 2.4-29.5C. Water temperatures below 6C are unsuitable for feeding however. Salinity range in the sea is 0.1-14.6 and this is the most euryhaline sturgeon in the Caspian Sea. This species is the best swimmer among sturgeons in the Caspian Sea in terms of power to body weight and in the Volga River migration speed averages 110 km/day (although progress is only 17.6 km/day because of the current).

The effects of diazinon on haematological parameters was examined by Khoshbavar Rostami et al. (2005) who also found the LC50 was 4.98 mg/l over 96 hours. Hiedary et al. (2012) found bioaccumulation of copper, zinc and mercury in muscles and liver, influenced by their concentration in sediments and the physiological state of the fish. The levels did not constitute a human health threat.

Age and growth

Maximum age for accidental catches in the Caspian Sea off Azerbaijan is 21 years but most are 8-13 years old. Males mature at 11-13 years, the youngest at 7 years, and females at 14-17 years, the youngest at 8 years in the Kura River. Populations in the Kura River and Iranian rivers take the longest time to mature, have a slower growth rate and lower fecundity. Vecsei et al. (2007) give a maturity range of 5-17 years. Like other sturgeons, this species does not reproduce every year and in the Caspian and there is a 3-4 year gap between reproductive periods in any individual. Females live longer than males. Maximum life span is about 41 years.

Levin (1997) summarises the Volga spawning population as being age 6-28 years (11-16 years on average) with females 150-152 cm and 11-12 kg and males 128-130 cm and 6-7 kg. Spawning temperature is 16-22C.

The stock on the Iranian coast was estimated at 3.2 million fish weighing 18,500 tonnes with 6.7% of fish mature (Ivanov and Katunin, 2001).

Studies in 2007 along the whole Iranian coast when 50 stations were sampled in waters less than 10 m deep, found this species to comprise 11.8% of the absolute frequency and 38.7% of the biomass of the total sturgeon catch, second after A. persicus (Iranian Fisheries Research Organization Newsletter, 51:2, 2007).

Von Bertalanffy growth parameters in Iranian females are L = 213 cm and K = 0.062 or 188 cm and 0.104 and for males 190 cm and 0.083 or 171 cm and 0.113 depending on the methodology used. Total mortality (Z) was 0.52-1.1 for females and 0.62-1.1 for males, natural mortality (M) was 0.07 for females and 0.08 for males, fishing mortality (F) was 1.03 for females and 0.54 for males, and optimum fishing mortality was (F) 0.42 for females and 0.30 for males (Iranian Fisheries Research and Training Organization Newsletter, 16:4-5, 1997). Samples taken from the whole Caspian shore of Iran from 2002 to 2004 had growth parameters ∞ = 219 cm and K = 0.06 year-1 (www.shilat.com, downloaded 28 February 2007). Yelghi et al. (2007) found maximum age frequencies for fish from the southeastern Caspian Sea were were 9-13 years for male and 12-13 years for females. Brood fishes more than 15 years old formed little of the total catch. The oldest and largest individuals were 17 years and 156 cm for males and 27 years and 178 cm for females. Growth was negative allometric. Bakhshalizadeh et al. (2012) found a maximum age of 29 years for samples from the commercial Iranian fishery from 2008 to 2010. This study also gave the asymptotic length (L) as 153.69 cm and 131.02 for females and males respectively, a growth coefficient (K) of 0.08 and 0.15 per year, and a total mortality coefficient (Z) of 0.79 and 1.08 per year. Annual mortality rates were 55% for females and 66% for males.

Food

Young specimens feed on crustaceans, older fish on chironomid larvae and the oldest specimens on fish (Rostami, 1961b). Azari Takami et al. (1980) found adults to consume gobies (Gobiidae) and kilka (Clupeonella) with the clams Abra ovata and Cerastoderma umbonatum as secondary items in Iran. In the Caspian Sea off Azerbaijan, Zarbalieva (1987) found that the polychaete worm Nereis diversicolor (82.7% by weight) dominated in the diet of sturgeons 20-80 cm long, being replaced by the mollusc Abra ovata (88.6%) at 90-120 cm and by Clupeonella spp. (65.1%) and Abra ovata (31.5%) at 125-140. Sturgeons 50-80 cm long also took the crab Rhithropanopeus harrisii (21.2%). Other foods include Rutilus rutilus (and presumably R. caspicus) Cobitis taenia (presumably C. keyvani), mysids, cumaceans, and amphipods. Gobies are generally of lesser importance than clupeids. Hashemyan et al. (2005) found diet in A. persicus, A. stellatus and A. nudiventris in coastal waters of Mazandaran and Golestan at depths less than 20 m to consist of annelids (50.8%), amphipods (41.5%), small fish 4.8%), decapods (2%) and bivalves (0.9%). Fish shorter than 40 cm fed mostly on shrimps, polychaetes and gammarids, 41-80 cm fish fed on shrimps, gammarids, polychaetes, bivalves and smaller fish, while fish greater than 80 cm fed mostly on shrimps and smaller fish. Haddadi Moghadam et al. (2009) studied diet in fish collected in summer and winter in the south Caspian Sea from 2004 to 2006. Food items were fishes (Neogobius sp., Atherina caspia, Clupeonella cultriventris (= caspia) and invertebrates (polychaete worms such as Ampharetidae and Nereis diversicolor; crustaceans such as Gammarus and Paramysis; and the bivalve mollusc Abra ovata). The diet varied with season and size group and was similar to A. persicus.

In rivers, juveniles feed on gammarids, chironomid larvae, mysids and worms. Spawning fish eat little or no food and, having used up much of their fat reserves, return to their feeding grounds in the sea immediately after spawning. This downstream migration varies from 70 to 80 km/day.

Reproduction

The peak migration in Iran is in April. There is also a peak run in fall (September-October) in the Kura River, and probably in Iran too (see below), but it is much less important than the spring run (Berg, 1959). Migrations in the Kura and Safid rivers can be found year round outside these peaks. The spring run in the Kura begins at about 10C and peaks at 18C, the runs decline in warmer summer temperatures and the fall run begins as water cools. Water level is also an important factor influencing runs and spawning. Water level fluctuations exceeding 0.2-0.5 m causes spawning to stop as fish migrate to deeper water. Summer and fall run fish do not spawn until the following year. Males arrive on the spawning ground before females and stay up to 6 weeks; females stay only 10-12 days. The Volga run begins in March-April with a peak in May but continues to October-November (Levin, 1997).

Up to 950,000 adhesive eggs are laid although in rivers of the southern Caspian absolute fecundity is lower, 35,400-362,900 eggs in the Kura River for example. Fertility is higher in the Volga compared to the Safid River (Iranian Fisheries Research and Training Organization Newsletter, 17:6, 1997). The spawning period in the Kura River is April-September at 15-29C. Fish may leap out of the water during spawning and scrape their bodies on the bottom, leaving scratches and bruises. Eggs are deposited over gravel, pebbles, or stones mixed with shell fragments and coarse sand in the river bed or on flooded banks at a current velocity of 0.7-1.8 m/sec. A gravel bottom and a current speed of 1.2-1.5 m/sec are ideal. Eggs are round to ovate, brownish-grey and up to 3.2 mm in diameter. The adult loses 25-30% of its weight after spawning and females are only ready to spawn again after 5-6 years and males after 3-4 years. Spawning occurs at 15-26C. Incubation takes 44-80 hours at 20-28C. Young fish descend to the sea at 3-4 months of age but in some populations this occurs immediately after hatching, taking only 12-15 days.

Moghim et al. (2000) have used ultrasonography to determine sex and maturity stage of this sturgeon. Sex determination had a 97.2% accuracy and took 30 seconds or less per fish. This non-invasive technique reduces stress and enables immature females caught at sea to be released.

Parasites and predators

Niak et al. (1970) report infestations of the ciliate Trichodina sp. in sturgeons (species unspecified) in breeding ponds in Iran. Golvan and Mokhayer (1973) record the acanthocephalan Leptorhynchoides plagicephalus and describe a new species, Corynosoma caspicum, from this sturgeon in Iran. The coelenterate Polypodium hydriforme is recorded from the eggs of this sturgeon in the Safid Rud. Mokhayer and Anwar (1973) report on sturgeon parasites in general (see under Acipenser gueldenstaedtii). Mokhayer (1976b) also reports gas bubble disease in Iranian sturgeons without specifying the species of sturgeon as well as the monogenetic trematodes Diclobothrium armatum and Nitzschia sturionis. Larvae of the nematode Anisakis is reported from this species in Iran (Eslami and Mokhayer, 1977). Mokhayer (1989) reports metacercariae of the eye fluke, Diplostomum spathaceum from this species in Iran, which can cause complete blindness and death in commercially important species. Sattari et al. (2001) found the following parasites in fish from the southwest Caspian Sea: Skrjabinopsolus semiarmatus, Leptorhynchoides plagicephalus, Cucullanus sphaerocephalus, Eubothrium acipenserinum, Bothriomonus fallax, Eustrongylides excisus, Aniskais sp., Amphilina foliacea and Corynosoma strumosum. Hajimoradloo (2002) records the nematode Cystoopsis acipenseris in adult fish. Pazooki and Masoumian (2004) report on blood parasites form fish caught at Anzali, recording Cryptobia acipenseris and Haemogregarina acipenseris. These parasites caused no pathological effects in the wild fish but can lead to severe infections and cause anaemia on fish farms. Sattari and Mokhayer (2005a; 2005b) recorded the occurrence of parasites in this species from the Iranian southwestern and central coast of the Caspian Sea. The species found were the nematodes Cucullanus sphaerocephalus, Eustrongyloides excisus and Anisakis sp., the cestodes Eubothrium acipenserinum, Amphilina foliacea and Bothrimonus fallax, the acanthocephalans Leptorhynchoides plagicephalus and Corynosoma strumosum, the digenean trematode Skrjabinopsolus semiarmatus. General conclusions were that the diversity of parasites was less in Iranian waters than in the northern Caspian Sea, perhaps a reflection of the more varied habitat, its productivity and the carbonate ions differing between the two regions. The diversity of parasite seems to have declined over time also, perhaps as a result of unfavourable environmental conditions, particularly in the freshwater ecosystem which limits the waters available for spawning and parasite acquisition. Shenavar Masouleh et al. (2006) found hatchery fingerlings to harbour Diplostomum spathaceum, Trichodina sp. and Gyrodactylus sp. Ebrahimi and Malek (2007) found the helminths Cucullanus sphaerocephalus, Skrjabinopsolus semiarmatus, Leptorhynchoides plagicephalus and Eustrongylides excisus. Rajabpour et al. (2008) recorded helminth parasites from fish at three coastal stations in the southeast Caspian Sea, namely the nematode Cucullanus sphaerocephalus, the digenean Skrjabinopsolus semiarmatus, the acanthocephalan Leptorhynchoides plagicephalus and the cestode Amphilina foliacea. Barzegar and Jalali (2009), in their summary of crustacean parasites of Iranian fishes, recorded Pseudotracheliastes stellatus from this sturgeon.

Predators are most evident on the young and include Silurus glanis and various gobies (Gobiidae) while eggs are taken by Blicca bjoerkna, Pelecus cultratus, Gobio sp., and gobies.

Economic importance

Uzun burun are known from a Neolithic site on the eastern Caspian shore in the former Soviet Union from about 6000 years ago (Tsepkin, 1986).

This sturgeon provided the majority of the caviar produced in Iran according to reports from the 1960s and beginning of the 1970s (Vladykov, 1964; RaLonde, 1970b), 70% of the total catch according to commercial suppliers in 1995. It is reputed to have the tastiest flesh and also the best caviar (Ricker, 1970) but others maintain beluga caviar is the best. Farid-Pak (no date) gives an average yield of 1.5-2.0 kg for each female in the 1950s in Iran. Catch records for the Safid River in 1930-1935 showed that 31.7% of fish were caught in May, 18.1% in April and 9.6% in June, with a small peak in October of 7.9%. Nevraev (1929) records catches of this species varying from 22,278 to 43,593 individuals in the Astara region of Iran for the period 1901-1902 to 1913-1914, for the Safid Rud region 5536 to 12,670 individuals for the period 1899-1900 to 1913-1914, for the Mazandaran region 846 to 1490 individuals for 1906-1907 to 1913-1914, and for the Astrabad (= Gorgan) region 2613 to 5160 individuals for 1902-1903 to 1913-1914. Vladykov (1964) records average yearly catches in Iran of this species (including some A. nudiventris with small eggs) from 1927/28-1931/32 to 1957/58-1961/62 with ranges of 59,291-301,218 kg body weight (9.7-23.8% of the total sturgeon catch; 33.8% in another five-year period when weight was lower than the maximum shown here) and 8246-77,780 kg caviar (10.0-48.2%; total range 9.5-54.5%). RaLonde and Walczak (1970b) summarise yields for the years 1963 to 1967 in Iran of meat and caviar as 385.2 tonnes (100.4 tonnes), 450.8 (99.3), 436.6 (98.9), 564.4 (113.0), and 584.7 (106.5) respectively. Hassan Nia (1995) analysed the stocks of this species for a 61-year period (1927-1987) and calculated projected yields for the period 1988-1992. Actual yields proved to be the same as projected yields. The catch in the northern Caspian Sea reached 13,200 tonnes in the latter half of the 1970s.

This species has not been used as extensively as others for studies on physiology, biochemistry and aquaculture. Some works include Taleban et al. (1998) who studied consumption of this fatty fish and found a reduction in mean serum triglycerides and very low lipoprotein cholesterol, and an increase in high density lipoprotein cholesterol; Pourgholam and Saeidi (2000) investigated haematological variables in juveniles and adults at different water temperatures; Hedayatifard et al. (2003) studied variation in fatty acids composition in cold storage and found the best holding time was three months; Pazhand et al. (2003) on the toxicity of the insecticide diazinon to fingerlings; Sadeghird et al. (2004) examined levels of zinc and copper in muscle tissue and caviar; Padjand et al. (2005) examined the toxic effects on fingerlings of the herbicide butachlor; Hedayatifard and Moeini (2007) determined the levels of fatty acids in fresh and frozen samples and their effects on shelf life; Hedayatifard and Yousefian (2007) looked at shelf life and changes of lipid and fatty acid composition in frozen storage; Mokaremi Rostami et al. (2007) on the effects on juveniles of creosote on mortality rate and blood biochemistry with significant differences from controls; Alipour et al. (2009) on fertilising ability of cryopreserved spermatozoa; Bahmani et al. (2009) on seasonal fluctuations of sex steroids in farmed 7-year-old fish; Asadi et al. (2009) on serum biochemical parameters; Hedayatifard and Aroujalian (2010) on packaging and shelf life; Filizadeh and Rajabi Islami (2011) on toxicity of the herbicide glyphosate; etc.

The use of 2000 p.p.m. potassium sorbate in processing caviar from this species gives a better quality product than caviar without preservatives (Salmani, 1995).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaculture and aquaria and as food.

Conservation

See also under A. gueldenstaedtii. Lelek (1987) lists this species as vulnerable and Birstein (1993) as intermediate in status. It is now rare in the Safid and Gorgan rivers of Iran because of dam construction, which inhibits the spawning migration, and irrigation control structures near river mouths. The ban on sea fishing in 1962 by Soviet authorities led to an increased abundance of this species. Artificial spawning sites with gravel 3-10 cm in diameter have proved useful in the former U.S.S.R. and stocking is well established with up to 23 million young being released in the Volga area annually in the mid-1970s. However Veshchev (1995) reports that the population of this species in the Volga could be lost, and this doubtless mirrors the situation in other Caspian Sea states including Iran. About 30% of all individuals caught in the Caspian in the late 1980s were hatchery stock (De Meulenaer and Raymakers, 1996). Abdolhay et al. (2006) report on 193 adults caught in 1998 which produced 623,000 million fingerlings while in 2002, 290 breeders were caught and 67 produced 1.3 million fingerlings. Mohseni et al., (2000) have studied effective stocking density of eggs and larvae in incubators and rearing tanks in order to maximise production and avoid various morphological deformities. Moghim et al. (no date) note that juveniles of this species are caught in the beach seine fishery for other species in Mazandaran. During 2001-2002, 23,760 seine hauls had a by-catch of 37% for this species among sturgeons.

Khodorevskaya et al. (1997) summarises the decline of this species in the Volga and Ural rivers. The problems are the same for all sturgeons, namely flow alterations affecting the volume of water on the spawning grounds, reduction in numbers reaching the these grounds through poaching, and increased pollution affecting reproductive efficiency. Studies on heavy metal contamination (Zn, Cu, Cd,, Pb and Hg) of both flesh and caviar in Iran, however, showed levels were below the maxima allowed for consumption, based on international standards (Sadeghi Rad et al., 2005; Abtahi et al. 2007). The median lethal concentration of suspended sediment from the Safid River has been studied by Garakouei et al. (2009); who found this species showed a lower tolerance than A. persicus.

Kiabi et al. (1999) consider this species to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, abundant in numbers, habitat destruction, widespread range (75% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin. Nezami et al. (2000) maintain that despite artificial spawning and fingerling production, restoration of this species in Iran was not very successful. Mostafavi (2007) lists it as vulnerable in the Talar River, Mazandaran. Critically endangered in Turkey (Fricke et al., 2007). Under IUCN and Appendix II of CITES, this species is now endangered (Vecsei et al., 2007).

Artificial breeding has been carried out with this species in Iran using hormones (I.F.R.O. Newsletter, 30-31:4, 2002). In contrast to other sturgeons, this species does not respond well to pituitary injections used to stimulate artificial reproduction. Pourkazemi (2006) examined haematological parameters and found wide fluctuations, with female spawners in particular differing in sexual maturity and physiological state. Although fish do respond to pituitary injections, the oocytes do not follow a normal course to maturity, remaining in the ovary. Oocytes at stage IV had overripe or degenerated oocytes. When overdosed with pituitary extract, ovulation occurred but oocytes were not mature and could not be fertilised. Degeneration of the egg membrane was found in 82% of spawners caught in the wild, presumably due to pollution. Baradaran Tahouri (1994) examined the effects of pond fertilisation on growth. Haddadi Moghaddam et al. (2001) studied the growth rate of this sturgeon in fertilised earthen ponds with added Daphnia. Shahsavani et al. (2001) determined blood parameters for fingerlings in a Gilan fish farm. Bahmani et al. (2006) recommended alleviating stress during capture, handling, transport and confinement, selecting breeders with suitable morphology and correct stage of sexual maturity, and using the hormone GnRH with domperidone as a substitute for pituitary extract. Luteinizing hormone releasing hormone analogue (LHRHa) was also found to be effective at 20.0-31.2 μg/kg body weight (Behmanesh, 2002). Kazemi et al. (2003) give a detailed histological study of the oocytes of this species. Caviar and fingerlings have been produced from farmed breeders (Iranian Fisheries Research Organization Newsletter, 49:3, 2006).). Sexual maturity was stimulated by injection of GnRH and anti-dopamine, eggs were extracted surgically, of which more than 80% hatched successfully using sperm taken by using tubes, and caviar and flesh harvested from one fish was comparable to natural samples.

Abdolhay and Tahori (2006) give fingerling production as:-

Process/Year 2000 2001 2002 2003 2004
Female broodstock captured 101 58 43 70 52
Injected broodstock 43 38 67 42 12
Spawning rate * (%) 60.4 50 49 63 50
Fertilisation rate (%) 55 58.6 51 51 83
Survival rate in incubators (%) 23 49.6 46 44 77
Survival rate in tanks (%) 54 93.5 60 72 77
Stocking density in ponds (fish/ha) 92,500 44,812 68,000 90,000 92,000
Survival rate in ponds (%) 12.2 67.7 38 61 86
Fingerling production (x 1000) 226 820 13,009 196 314

* Rate of response to hormone injection

Moghim et al. (2002) used ultrasonography to determine sex and maturity. This is important in management of endangered species when external sexual dimorphism is not apparent. Accuracy was 97.2% and was around 30 seconds or less per fish.

Further work

See under A. gueldenstaedtii.

Sources

See under the family account. Wossugh-Zamani (1991a) gives an account of this species in Farsi. Derzhavin (1922) and Borzenko (1942) are older works giving details of the biology of this species.

Iranian material: Hatchery adults examined at Bandar-e Anzali.

Comparative material: BM(NH) 1873.4.21:21-23, 2, 99.6-236.6 mm total length, Russia, Black Sea (no other locality data); BM(NH) 1929.8.7:4-5 and BM(NH) 1930.3.21:2, 3, 246.4-308.2 mm total length, Ukraine, Sebastopol, Black Sea (no other locality data).

Genus Huso
Brandt and Ratzeberg, 1833

This genus is characterised by a large and crescentic mouth (small and transverse in Acipenser) and by the gill membranes being joined to each other and free of the isthmus (joined to the isthmus in Acipenser). The snout is short and blunt although Caspian Sea stocks have a longer snout than Black Sea ones. The barbels are flattened laterally and gill rakers are rod-like. There are only 2 species in the genus, one in the Caspian, Black and Adriatic seas and one in the Amur River of eastern Asia.

Birstein and DeSalle (1998) using cytochrome b and 12S and 16S rRNA genes found that Huso may not be distinct from Acipenser. Vasil'eva et al. (2009) using cytogenetic and morphological characters also advocate reverting to the original genus Acipenser for Huso species.

Huso huso
(Linnaeus, 1758)

Huso huso, Iran, 1959, courtesy of Hamid Niksirat (no other data)
Huso huso, Iran, 1959, courtesy of Hamid Niksirat (no other data)

Common names

فيل ماهي (= fil mahi, filmahi or philmahi meaning elephant fish), beluga, beloga, سگ ماهي (sag mahi, meaning dogfish), ماهي خاويار (= mahi-ye kaviar, meaning caviar fish), mahi kaviar-e bozorg (= big caviar fish).

[bolka, Kur bolkasi for natio kurensis, ag-kulag-nyarya, gyuz'gi-burun in Azerbaijanian; doku (akvalyk) in Turkmenian; beluga in Russian; great, giant or European sturgeon].

Systematics

Acipenser huso was originally described from the Danube and rivers of Russia.

Huso huso caspicus Babushkin, 1942 was described as the subspecies of the Caspian Sea basin (with natio kurensis Babushkin, 1942 from the Kura River (also spelt incorrectly cyrensis and curensis)) but Berg (1948-1949) considered Caspian-Volga populations to be typical and this subspecies description as unnecessary. No types of Huso huso caspicus are known (Eschmeyer et al., 1996).

Huso ichthyocolla Bonaparte, 1846 is a synonym (Eschmeyer et al., 1996) and a nomen nudum (Holčk, 1989). Acipenser brandtii Gnther, 1870 from the "Black and Caspian Seas, with their rivers" is a hybrid of Huso huso and Acipenser nudiventris based on Acipenser schypa (in part) of Brandt and Ratzeberg (Berg, 1948-1949; Eschmeyer et al., 1996). M. Pourkazemi in PADECO (2002) considers there are two sub-populations in Iran and Ghadirnejad et al. (2008) using microsatellite loci concluded that there were possibly two populations in the southern Caspian Sea.

Hybrids of Huso with Acipenser have been bred by the Aquaculture Department of the Iranian Fisheries Research and Training Organization (Iranian Fisheries Research and Training Organization Newsletter, 3:3, 1994; Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 6, 1996; Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 41, 1997) and natural hybrids with A. gueldenstaedtii, A. nudiventris and A. stellatus are reported from the Caspian Sea (Berg, 1948-1949). Yarmohammadi et al. (2012) were able to identify besters (female Huso and male A. ruthenus hybrids) from the International Sturgeon Research Institute in Rasht using the AFLP molecular technique.

Key characters

This species is identified by its very large, crescent-shaped mouth (small and transverse in other sturgeons) and the gill membranes being joined as a fold across the isthmus.

Morphology

The greatest body depth is slightly anterior to the middle of the body and large fish appear humpbacked. The lower lip is interrupted at its centre. Barbels are flat posteriorly, reach almost to the mouth and have foliate appendages. Experiments on ablading barbels (clipping one, two and four barbels) in 1+ age fish showed no growth differences with an unclipped control (Abasali Zadeh, 2003). The dorsal scutes are covered with skin in sexually mature fish, lateral scutes are smooth and ventro-lateral scutes hidden beneath the skin.

Dorsal fin rays 48-81 and anal fin rays 22-41. Dorsal scutes 9-17, lateral scutes 28-60 and ventral scutes 7-14. Scutes in adults may be reabsorbed. The skin is covered in small denticles. Gill rakers 16-36.

The chromosome number is 2n=118 3 or 115 1 (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 43, 1996; Iranian Fisheries Research and Training Organization Newsletter, 8:5, 1995), 2n=116 1 (Nowruz Fashkhami, 1996), 2n=118 2 or 2n=116 4 (Klinkhardt et al., 1995), 2n=117 (Nowruz Fashkhami and Khosroshahi, 1999). Sex chromosomes are absent or weakly differentiated in the genome and DNA markers cannot be used to sex fish; minor surgery has to be used (Keyvan Shokoo et al., 2004; Keyvanshokooh et al., 2007).

Sexual dimorphism

None found in morphometric and meristic characters although females are said to be longer and heavier than males of the same age.

Colour

The back is ash-grey, blue-grey to greenish or dark brown, sometimes black, fading to a white or cream belly. The contrast between the dark back and lighter rest of the body is marked. Young often have a metallic sheen which fades with age. The snout is yellowish.

Size

Attained weights of 1228 kg yielding 246 kg of caviar or 7.7 million eggs (Berg, 1948-1949), even 1600 kg (Farid-Pak, no date), and there are newspaper and other reports of fish 1200 kg and 6 m (Ottawa Citizen 14 May 1986) or even 3200 kg and 9 m but such large fish are not seen today and the largest sizes are probably exaggerations. Modern catches are mostly much smaller than these exceptionally large fish. A recent record with the specimen preserved in the Astrakhan Museum in Russia is given in Sternin and Dor (1993) for a fish from the Volga River in 1989 weighing about 980 kg, 4.3 m long and yielding about 110 kg of caviar (Iran News, 14 July 1998, gives 988 kg, 120 kg of caviar and an age of 60 years, presumably the same fish). A photograph of a 1908 capture at Astrakhan in Stein and Bain (1981) shows a fish weighing about 400 lbs (181.4 kg) containing 200 lbs (90.7 kg) of caviar worth more than $69,000 in 1981. Tsepkin and Sokolov (1971) give some examples of large fish from former Soviet waters. Birstein et al. (1997) consider this species to be the largest freshwater fish.

The mean weight of Caspian Sea fish decreased from 110 kg in the early 1970s to 57 kg in 1991 (De Meulenaer and Raymakers, 1996).

Up to 2.83 m and 450 kg generally in Iran (Azari Takami et al., 1980) but see below for news reports. Belugas up to 960 kg tried to enter the Atrak River in 1836 (Vladykov, 1964). The longest fil mahi caught in Iranian waters is apparently one taken on 23 February 1989 by Turkmen fishermen at Shilat-e Nahee 4 in Mazandaran (see Abzeeyan, Tehran, July 1991, page 3). It had a fork length of 4.5 m, a total weight of 725 kg and a caviar weight of 98.2 kg. This individual was worth U.S.$140,000 (Abzeeyan, Tehran, November 1992, page 57). The heaviest fish from Iran is one reported by Hossein Aimani at 3000 lbs (1360.8 kg) from near Babol in 1973 (www.amarillonet.com/stories/120599/bus_LQ7659.shtml, downloaded 7 March 2000). Mobayen (1968) gives the largest Iranian specimen as 4.2 m and 850 kg. Anonymous (1991a) and Sternin and Dor (1993) cite a fish of 1742 lb (= about 791 kg), 7.5 feet long (= about 2.3 m) and yielding 220 lb (= about 100 kg) of caviar from Iran in 1989, the largest caught for 20 years; this may be the same fish as the previous one as confusion in weights and lengths are common in reports of large fishes. Other large specimens were taken at Mahmudabad, Mazandaran on 28 October 1992, measuring 3.2 m, weighing 430 kg and with 61.2 kg of caviar (Abzeeyan, Tehran, November 1992, page 13), at Bandar-e Torkeman (= Bandar-e Shah) weighing 320 and 410 kg giving 110 kg of caviar for the two fish (Abzeeyan, Tehran 4(1):IIX, 1993), at Bandar-e Torkeman, Mazandaran on 27 March 1993, measuring 4.0 m, weighing 550 kg and with 81 kg of caviar (Abzeeyan, Tehran, 4(2):47, 1993), and in Mazandaran one measuring 3.0 m fork length and 3.4 m total length, weighing 960 kg and yielding 62.5 kg of caviar (Iranian Fisheries Research and Training Organization Newsletter, 5:8, 1994). Newspaper reports in 1996 listed a fish of 500 kg with 54 kg of caviar worth $107,000 and a fish caught in October 1997 at Babol Sar weighed 300 kg, measured 3 m in length and had 45.1 kg of caviar. In 1998, one fish 3.4 m long yielded 43 kg of caviar (Reuters), a fish caught off Bandar-e Torkeman on 2 February measured 3.75 m, weighed 405 kg and yielded 50 kg of caviar (IRNA (Islamic Republic News Agency), 3 February 1998), one caught off Bandar Anzali on 25 October weighed 360 kg, was 3 m long and yielded 24 kg of caviar and "meat" worth 3.6 million rials (IRNA, 26 October 1998), one caught off Nour, Mazandaran on 15 November measured 3.5 m, weighed 450 kg, yielded 53 kg of caviar and was 30 years old (IRNA, 16 November 1998), and one caught off Kianshahr, Gilan weighed 290 kg, was 3.5 m long and yielded 50.6 kg of caviar worth 100 million rials (IRNA, 24 November 1998). In 1999 newspaper reports included one caught off Bandar Anzali weighing 155 kg, carrying 31 kg of caviar worth $12,400 (IRNA, 31 October 1999), one caught off Talesh weighing 120 kg with 23.5 kg of caviar worth 150-200 million rials (IRNA, 5 December 1999), and one caught off Bandar-e Torkman weighing over 405 kg with over 52 kg of caviar worth 500 million rials (IRNA, 14 December 1999). One fish caught near Bandar Anzali in weighed 370 kg and yielded 51 kg of caviar (IRNA, 28 October 2002).

Distribution

Found in the Adriatic, Black and Caspian seas and their drainages. Derzhavin (1934) reported it from the Babol, Sorkh and Gorgan rivers but it was rare in the Safid River, although reported up to Kisom and quite abundant in the sea off its mouth. Nedoshivin and Iljin (1927) record this species from 10 river mouths while A. stellatus and A. gueldenstaedtii are reported from 18; the 10 river mouths are Yusufabad, Musachai, Hasan Kiadeh, Dastak, Safid, Kasumabad, Chalkarud, Sardabrud, Chalus and Kheirud. Kozhin (1957), Rostami (1961) and Armantrout (1980) stated that it enters the Astara, Safid, Babol and Gorgan rivers and the Anzali and Gorgan mordabs. It comprised only 0.5% in numbers and 2.5% in weight of the Safid River catch in 1914-1915 (Nedoshivin and Iljin, 1927). Large numbers were caught in the sea off Gasan-kuli in Turkmenistan near the Iranian border (Berg, 1948-1949). Also reported from Hasan Kiadeh by V. D. Vladykov based on field work notes made in 1962. More recently reported from the Gorgan and Safid rivers, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea by Kiabi et al. (1999) and Abdoli and Naderi (2009), from the Safid River by Abbasi et al. (1999) and from the Safid, Gorgan and Tedjen rivers. This species was not caught in a survey along the Iranian coast in 2001 (Ivanov and Katunin, 2001). In 2004 there were plans to introduce this species to isolated, natural waters bodies in Fars Province (H. R. Esmaeili, in litt., 2004).

Zoogeography

Presumably a relict of past isolation of the Black-Caspian seas from the world ocean.

Habitat

This sturgeon is found in large concentrations in the eastern coastal region of the south Caspian Sea in all seasons. It is rare in trawl catches, possibly because it has a more pelagic life than other sturgeons. Fil mahi descend to greater depths than other sturgeons, 100-140 m in the Caspian and to 180 m in the Black Sea. There is no seasonal variation in depth distribution in the south Caspian Sea in contrast to the middle Caspian (Legeza, 1972; 1973). Only the young are found in shallow, warm areas. On the spawning migration, this sturgeon usually follows the deepest part of the river.

Most of this sturgeon's life is spent in the sea and it ascends rivers only to spawn. The new-born sturgeon returns to the sea. Farabi et al. (2007) examined salinity tolerance and physiology of juvenile fish in Iran. Only the youngest fish showed mortality on direct transfer from fresh to estuarine and Caspian sea water. Adults are typically found on silty or muddy bottoms in the sea but may be found on shelly and coarse sand at a temperature range of 5.6-29.3C and depths of 5-140 m. In the southeastern Caspian it remains below 30 m in winter, entering shallower water at depths of 10-20 m in spring as the temperature ameliorates, dispersing throughout the southeastern Caspian in summer and migrating into Iranian waters in autumn (Legeza, 1972; Filippov, 1976). Depth distribution depends in large part on the available food supplies.

Oxygen requirements are high, averaging about 14 mg/l, but they can survive at 2-3 mg/l. Salinities up to 22 are tolerated. Feeding occurs over a temperature range of 0.5-30C and the spawning migration at a range of 6-21C. The highest densities in the southern Caspian Sea occur at 22-29C, feeding in winter at 10-12C (Caspian Sea Biodiversity Database, www.caspianenvironment.org).

Age and growth

Males become sexually mature at age 9-16 years and females at 12-22 years, varying with the spawning river. This is a very late maturation age among fishes world-wide. Spawning intervals are 4-7 years for males and 5-7 years for females (Vecsei et al., 2002; see below for other ranges but certainly intervals are long for a fish species). Spring-spawning females (see below) first spawn at 201-209 cm, 50-60 kg and 17 years. Winter-spawning females first spawn at 181-190 cm, 30-39 kg and 16 years. Most spring females are 230-300 cm long, weigh 80-160 kg and are 23-28 years of age. Most winter females are 201-300 cm, 50-160 kg and 17-26 years (Raspopov and Dubinin, 1990). Spawning populations have a complex age structure, the Volga River in 1936 had 50 age groups for example but only 28 in 1964. There has been a trend for spawners to be younger. Average catches in former Soviet waters of the Caspian Sea now weigh only 77 pounds (34.9 kg) each, a decline caused by overfishing (Los Angeles Times, Part A, page 1, 28 August 1993). A life span of 150 years was reputed for this species but the greatest known age for a Caspian fish is 75 years (Berg, 1948-1949). Most Caspian fish are now less than 20 years old and made up of individuals from re-stocking programmes (De Meulenaer and Raymakers, 1996). Raspopov (1993a; 1993b) gives the life cycle of Volga River fish as 56 years, although this is not the maximum age. Kura River sturgeon grow more slowly and mature later than sturgeon from the Volga River. Growth in this species is rapid with 1-year-old fish in the Caspian being 51 cm long and weighing 571 g. Growth is slower in the Caspian than the Black Sea because of the decrease in numbers of Alosa spp., the prime food item. Growth is also slower in the south Caspian than the north (Caspian Sea Biodiversity Database, www.caspianenvironment.org). Hedayatai et al. (2009) were able to correlate weight and length with immature male gonadal stage, but not for females, in work directed to reducing maturation time. Moghim et al. (2008) studied sex ratio along the Iranian coast for the years 1990-2003 and found females dominated at 60-80% of landed fish. Immature females decreased from 71 to 47% of the catch.

Levin (1997) summarises the spawning population of the Volga River over the last 10 years as follows although he notes this population is almost extinct. Rarely spawners enter between August and October and breed after a winter hibernation. Other fish enter from December to May with a peak from February to March. Peak spawning is in May with a downstream migration to the Caspian Sea from June to September. Females, comprising 20-24% of the spawning population, average 236-261 cm and 106-160 kg and are 17-21 years old with fish larger than 400 cm being very rare. Males are 199-204 cm and 48-55 kg and are 11-18 years old. Spawning occurs at 9-11C.

Farid-Pak (no date) gives approximate weights for Iranian beluga of 75-100 kg and 2.0-2.5 m, and a yield of 17-20 kg of caviar per female. 2608 beluga from Astara in Azerbaijan averaged 168 cm for males and 192 cm for females.

Von Bertalanffy growth parameters in Iranian females are L = 320 cm and K = 0.065 for juveniles, 450 cm and 0.029 for the middle stanza and 533 cm and 0.023 for older fish and for males 270 cm and 0.086 or 302 cm and 0.072, depending on the methodology used. Total mortality (Z) was 0.21-0.67 for females and 0.22-0.75 for males, natural mortality (M) was 0.03 for females and 0.05 for males, fishing mortality (F) was 0.45 for females and 0.33 for males, and optimum fishing mortality was (F) 0.07 for females and 0.16 for males (Iranian Fisheries Research and Training Organization Newsletter, 16:4-5, 1997). Taghavi Motlagh (2001) gives more complete data (on which the previous summary was based) on growth, mortality and yield-per-recruit on this species from 1995 to 1999 in the Iranian Caspian Sea. He concluded that fishing mortality should be stopped. Maximum age in his sample was 46 years.

Food

In contrast to other sturgeons, this species is a pelagic predator as adults. Even sea birds and seals may be eaten. However, the introduced polychaete worm Nereis is now a mainstay of the diet of this species in the north Caspian Sea. Other foods are molluscs, formerly a main food, and small fish such as Rutilus rutilus (and presumably R. caspicus)and gobies (Gobiidae). Fish are the main diet item when large, invertebrates when young. This species needs to find thick concentrations of small or large fishes in order to feed actively; in the north Caspian these are kilka and fish on migration at fishways and in the midde Caspian spawning atherinids and commercial herrings (Polyanina et al., 1999). The fish found by Azari Takami et al. (1980) in Iran were gobies, Cyprinus carpio, Liza, and Rutilus. Gobies are a favourite food item but bivalves and crustaceans are taken if fish are absent. Filippov (1976) notes that large specimens eat sturgeons such as sevryuga, kopur (Cyprinus carpio), mullets (Mugilidae), birds such as coots, and baby seals and because of its pelagic life takes the clupeids Alosa braschnikowii and Clupeonella caspia and also the shrimp Leander adspersus. Crabs are also eaten. The principal food as percent by weight in the southeastern Caspian was Neogobius fluviatilis (= pallasi) (up to 78.1%), gobies accounted for up to 81.2% and fish 81.6-100%. Crustaceans accounted for up to 7.8% and molluscs only up to 0.2%. The cyprinid, Chalcalburnus (= Alburnus) chalcoides, is also eaten (Mageramov and Zarbalieva, 1989).

Reproduction

Roux (1961a) maintained that this species did not reproduce in Iranian rivers but Rudin (1966) said that they inhabited the Safid and Gorgan rivers. The main spawning river was the Volga as 90% of the Caspian stock reproduced there, travelling as far up as the Moskva River. Males arrive at spawning sites before females. Despite their size, these sturgeons may leap out of the water on the spawning run and possibly during spawning. Adhesive eggs are deposited on sandy substrates, with rocky and gravelly bottoms near the bank, in the strong current of mid-river (1.5-2.0 m/sec.). Water temperatures are 9-17C and eggs develop in 9-10 days (Novikova, 1994; Vecsei et al., 2002). Spawning usually takes place at a depth of 4-15 m, sometimes as deep as 40 m. Weight loss after spawning may reach 50% and females are only ready to spawn again after 5-6 years and males after 3-4 years (4-8 and 4-7 years in Speer et al., 2000). The migration in the Volga River occurs year-round with peaks in spring (<30% of the stock) and autumn. The spring race reach the spawning beds in the same year, reproduce and return to the sea. The winter race, migrating in summer and fall, overwinter in the river and reproduce the following spring. The spring run is in March and April and the winter run in September and October. The chief spawning period in the Kura River is from the end of May to the beginning of June (Zakharyan, 1972) and fish were found as far up as Tbilisi (= Tiflis).

Fecundity reaches, exceptionally, 7,729,700 eggs but does not increase with age for fish of equal length and weight (Raspopov, 1987; Raspopov and Dubinin, 1990). Mean fecundity for the Volga stock was 531,600 eggs. Normal deposition of eggs is 500/sq m in the Volga but densities fell below 5/sq m in the 1980s, as low as 0.2/sq m and with an average of 1.5/sq m (Novikova, 1994). Kura River sturgeon are less fecund than Volga sturgeon. Egg diameter reaches 4.3 mm. Eggs are a dark silver and oval. Larvae hatch in 10-14 days, the yolk sac is absorbed in 10-14 days and feeding larvae move downstream at up to 60 km/day (Vecsei et al., 2002).

Parasites and predators

Niak et al. (1970) report infestations of the ciliate Trichodina sp. in sturgeons (species unspecified) in breeding ponds in Iran. Golvan and Mokhayer (1973) describe a new species of acanthocephalan, Corynosoma caspicum, and also Leptorhynchoides plagicephalus from this sturgeon in Iran. Mokhayer and Anwar (1973) report on sturgeon parasites in general (see under Acipenser gueldenstaedtii). Mokhayer (1976b) reports gas bubble disease in Iranian sturgeons without specifying the species of sturgeon as well as the monogenetic trematodes Diclobothrium armatum and Nitzschia sturionis. Pourgholam (1994) reports the coelenterate Polypodium hydriforme from this species caught on the Babol Sar and Bandar-e Torkeman fishing grounds in Mazandaran. Larvae of the nematode Anisakis simplex and the acanthocephalan Corynosoma strumosum are also reported from this species (Annual Bulletin 1993-94, Iranian Fisheries Research and Training Organization, Tehran, p. 48-49, 1995). Sattari et al. (2002) record Cucullanus sphaerocephalus, Eustrongylides excisus, Skrjabinopsolus semiarmatus, Anisakis sp., Eubothrium acipenserinum and Corynosoma strumosum, the fauna being similar to other sturgeons because of their piscivorous feeding. Gorogi (2006b) recorded the nematodes Cucullanus sphaerocephalus and Anisakis schupakovi, the cestode Eubothrium acipsenserinum and the acanthocephalans Leptorhynchoides plagicephalus and Corynosoma strumosum from Iranian waters. Sattari and Mokhayer (2005a; 2005b) recorded the occurrence of parasites in this species from the Iranian southwestern and central coast of the Caspian Sea. The species found were the nematodes Cucullanus sphaerocephalus, Eustrongyloides excisus and Anisakis sp., the cestode Eubothrium acipenserinum, the acanthocephalan Corynosoma strumosum, the digenean trematode Skrjabinopsolus semiarmatus. General conclusions were that the diversity of parasites was less in Iranian waters than in the northern Caspian Sea, perhaps a reflection of the more varied habitat, its productivity and the carbonate ions differing between the two regions. The diversity of parasite seems to have declined over time also, perhaps as a result of unfavourable environmental conditions, particularly in the freshwater ecosystem which limits the waters available for spawning and parasite acquisition. Shenavar Masouleh et al. (2006) found hatchery fingerlings to harbour Diplostomum spathaceum and Trichodina sp. Barzegar and Jalali (2009), in their summary of crustacean parasites of Iranian fishes, recorded Pseudotracheliastes stellatus from this sturgeon.

The fil mahi is so large that its predators are only effective on young fish. They include Sander lucioperca and Silurus glanis and, needless to say at all sizes, mankind.

Economic importance

This species provides the best caviar according to Borodin (1930). The large eggs fetch a higher price on the American market. Up to 80% (3000 kg in 2002) of the legal beluga caviar export is consumed in the U.S.A. (Hamilton, 2002). A 1227 kg specimen caught in Russian waters in 1924 gave 245 kg of caviar worth 189,350. In the 1990s, a 225 kg fil mahi could yield 22 kg of caviar worth $120,000 (Trickey, 1995). Catches in the Volga region in the 1970s were in the range 740-2650 tonnes and in the 1980s 460-900 t comprising 4.4-12.2% and 3.7-4.4% respectively by weight of the total catch of all sturgeons there. The highest catch in the Caspian Sea was in 1902-1907 (Birstein, 1993). Khodorevskaya et al. (1997) and Khodorevskaya (1999) summarise the decline in catches and make the startling observation that 96.3% of all fil mahi in the Volga River are hatchery reared.

Fil mahi were fished intensively off the Iranian coast in the southeastern Caspian and in 1950 amounted to 38.6% of the total sturgeon catch. During the five-year period 1957/1958 to 1961/1962 fil mahi catches in the Gorgan Division of the Iranian fishery varied between 86-90% of total Iranian catches. The Atrak River estuary area was particularly important for this species. Catches of the oldest age groups has declined and the proportion of young and immature fish has increased. Iranian rivers suitable for this sturgeon were the Safid and the Gorgan but both are now regulated so Iranian stocks are probably maintained by fish reproducing in the rivers of the former U.S.S.R. (Filippov, 1976). Fil mahi cannot be managed by Iranian authorities therefore. However the "Gharasoo" Research Station in Mazandaran is researching the culture and release of fil mahi up to 1 kg (Madbaygi, 1993b) and farming through pen culture in Gorgan Bay (Iranian Fisheries Research and Training Organization Newsletter, 11:6, 1996). Two million "roes" (presumably young fish) were released into the Caspian Sea from Mazandaran prior to 1 June 1995 with a further 2 million to be released later in the year (http://netiran.com/news/IRNA/html/950701IRGG08.html). In 1997, 852 fishermen were fishing for fil mahi on the northern Iranian coast (Anonymous, 1997c).

Farid-Pak (no date) gives the months of September-October and March-April as the most important for the fisheries of this species. Nevraev (1929) gives catch ranges of 109-3100 fil mahi individuals for the Astara region of Iran over the period from 1901-1902 to 1913-1914, for the Safid Rud region 104 to 730 individuals for the period 1899-1900 to 1913-1914, for the Mazandaran region 31 to 491 individuals for 1906-1907 to 1913-1914, and for the Astrabad (= Gorgan) region 688 to 1764 individuals for 1902-1903 to 1913-1914. Vladykov (1964) records average yearly catches in Iran of this species from 1927/28-1931/32 to 1957/58-1961/62 with ranges of 57,820-418,059 kg body weight (5.4-33.0% of the total sturgeon catch) and 2038-32,873 kg caviar (2.6-20.4%). There was an upward trend in caviar production from this species in the 1950s (Vladykov, 1964). RaLonde and Walczak (1970b) summarise yields for the years 1963 to 1967 in Iran of meat and caviar as 572.3 tonnes (40.1 tonnes), 583.5 (47.3), 575.8 (39.1), 458.1 (29.5), and 507.2 (30.0) respectively. A commercial house maintains (1995) that caviar from this species comprises only 3% of the total catch. Taghavi Motlagh (2001) noted a decline in the share of Iranian caviar production from 18% in 1971 to 4% in 2000.

This species has been studied in ponds as breeders are used to produce fingerlings which are then available as experimental fish for chemical and growth studies. Ghorbani et al. (2003) studied the influence of heavy metals on the level of alfa-amylase activity in the digestive tract and found decrease in enzyme activity was not significant. Karimzadeh et al. (2005) studied cytochrome P4501A1, a major isoenzyme in the monooxygenase system which can be induced by polycyclic aromatic hydrocarbon pollutants. Khoshbavar Rostami et al. (2006) studied the effects of polyaromatic hydrocarbons from Caspian Sea oil wells on 8.5 g fingerlings and found these chemicals to seriously affect the fish blood and enzyme systems. Khoshbavar Rostami et al. (2004; 2006) studied the organophosphate diazinon and its deleterious effects on haematological parameters in this sturgeon. Sharifpour et al. (2004) studied the effects of the insecticide endosulfan, sturgeon weighing 3-5 g showing irregular swimming, whirling, convulsions, with other conditions, and eventually death. Endosulfan is highly toxic to beluga fingerlings. Sudagar et al. (20050 examined the addition of betaine and methionine (an important nutrient and an enzyme) to the diet of juvenile beluga. The fish showed improved weight gain, weight gain percentage, specific growth rate, protein efficiency ratio, net protein utilisation, condition factor, survival, and price index at enrichment levels of 0.5% betaine and 1% methionine. Ghorbani et al. (2004) examined the influence of a series of microelements (zinc, nickel, cobalt, manganese, iron and copper) on the level of proteolytic enzymes and alkaline phosphatase activity (used for enzyme inmmunoassays) in the digestive tract of juvenile beluga. Most treatments showed the level of enzyme activity was less than the control. Shahsavani (2002) determined blood parameters of fingerlings from fish farms and found the fish to be healthy. Blood parameters are used to indicate physiological condition and sublethal stress due to endogenous and exogenous changes, hence the need to determine normal values. Askarian et al. (2006) looked at serum osmoregulatory parameters under different light regimes, one form of physical stressor in aquaculture of this endangered species. No differences in serum cortisol levels were found between treatments although elevations of serum cortisol, glucose and triglyceride occurred in a continuous dark regime. Gafarian et al. (2007) used probiotic bacillus in the feeding of larval sturgeon and found that it positively affected feeding efficiency and levels of carcass nutrient composition. Ebrahimi (2006) determined that the earliest time to transfer farmed larvae to a commercial diet from a natural one was 3-4 days after yolk sac absorption and the best time was 30 days at an average weight of 2 g. Khoshbavar-Rostami et al. (2007) examined the immune response to Aeromonas hydrophila bacterin. Soulati and Falahatkar (2007) looked at stress response in sub-yearlings exposed to air. Shamloufar et al. (2007) examined the sub-lethal effects of diazinon on haematological indices in juveniles. Akrami et al. (2008) studied the effect of prebiotic inulin levels and found it did not increase growth performance of juveniles. Askarian et al. (2008) examined the gastrointestinal tract for lactic acid bacteria and found the population levels to be significantly higher  than in Acipenser persicus. Bagheri et al. (2008) studied seasonal hormone fluctuation in fish raised in saline conditions at Bafgh, Yazd Province. Hedayati et al. (2008) studied blood indices of fish cultured in brackish water. Hosseini et al. (2008) examined the organochlorine content of four sturgeon species and found fil mahi had four times more than the next highest species (A. nudiventris); generally pollutants had been reduced compared to previous studies but some specimens exceeded guideline levels for food. Soltani et al. (2008) found that 100-200 mg/kg of vitamin C was optimum for rearing this sturgeon. Baghfalaki et al. (2009) carried out studies on seminal plasma indices in order to improve short and long-term storage of semen. Darvish Bastami et al. (2009) found that addition of Daphnia and Artemia extracts had positive outcomes on growth in juveniles. Akbari et al. (2009) studied the use of sperm extenders and found that they prolonged spermatozoa viability in short-term storage and prolonged sperm motility. Ghanbari et al. (2009) isolated Lactobacillus species, which ferment carbohydrates, from the intestine. Jalali et al. (2009) found that Artemia urmiana nauplii on enriched with HUFA and vitamin C and fed to larval sturgeon improves some growth and stress tolerance. Seifzadeh et al. (2009) examined microbial quality of packaged fillets of this sturgeon. Askarian and Kousha (2008) examined food ration on the acute stress response, those receiving a high ration performing better. Alizadeh et al. (2009) studied effects of different diets on energy levels and gonad development for fish reared in inland brackish water, this environment proving suitable. Askarian and Kousha (2009) studied photoperiod in rearing year-old fil mahi evaluated by growth (no effect) and serum parameters (various individual responses to stress. Falahatkar et al. (2009) examined dosages of vitamin C that enhanced immune responses to disease. Jalali et al. (2009) found that juveniles fed Ergosan, an algal product, had higher growth rates than a control group and certain haematological parameters were affected. Sepahdari et al. (2009) found various skin lesions in fish fed a diet containing aflatoxin B1 (a naturally occurring fungal toxin). Gharaei and Ghaffari (2010) found that serum biochemistry can be used as enzyme biomarkers to assess toxicity of methyl mercury in juveniles. Gharaei et al. (2010) studied accumulation of methylmercury in different tissues of hatchery juveniles fed four different concentrations of MeHg. Sepahdari et al. (2010) found deleterious changes in liver tissues n fish fed a diet containing aflatoxin B1. Yousefi et al. (2010) found nucleotides added to the diet of juveniles had a positive effect on stress tolerance. Alizadeh et al. (2011) studied seasonal changes of blood serum ions in brackish water, a proposed culture medium, at Bafgh in Yazd Province. Ebrahimi Dorcheh and Zare (2011) found that the optimum dietary level of lipid for fingerlings was 14%. Filizadeh and Rajabi Islami (2011) reported on on the toxicity of the herbicide glyphosate. Ghanbari and Jami (2011b) recorded Lactobacillus species from the guts of this species. Peik Mousavi et al. (2011) determined the role of methionine in whole body composition of juveniles. Rafatnezhad et al. (2011) stocked juveniles in fibreglass tanks at differing densities and found that water quality varied significantly and, as a result, growth. Ta'ati et al. (2011) found that growth performance and some immunophysiological indices improved when juveniles were fed diets containing the commercial prebiotic Immunoster (a brewers yeast cell wall derivative). Agh et al. (2012) examined first feeding strategies for hatchery larvae finding live food and manufactured diet improves weight gain, although pure live food increased survival. Yarmohammadi et al. (2011) found sex chromosomes were not differentiated sufficiently using AFLP to identify males and females at an early life stage. Jahanbakhshi et al. (2012) found that the insecticide cypermethrin to be highly toxic to juveniles. Jahanbakhshi et al. (2012) examined the use of plant protein to replace fish meal in feed for juveniles in hatcheries. Karimzadeh et al. (2012) used cytochrome P450 1A in this sturgeon as a biomarker for impact assessment of polycyclic hydrocarbons pollutants. Mohseni et al. (2012) investigated the best live food (Daphnia, chironomids, gammarids) and formulated diet in various combinations for larval fish and found chironomids plus formulated diet was best, other diets showing frequent cannibalism and higher mortality. Poursaeid et al. (2012) examined haemtological and cortisol values of female fish implanted with cortisol (to imitate chronic stress) after an endoscopic examination to assess gonad development. Falahatkar et al. (2013) evaluated the winter feeding rate in young-of-the-year and its effects on maintaining weight during short periods of winter starvation (1% body weight per day for commercial farming and 0.3% in overwintering ponds).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaculture and aquaria, as food and in textbooks.

Conservation

See also under A. gueldenstaedtii. Critically endangered in Turkey (Fricke et al., 2007). Despite loss of 99% of the Volga River spawning beds to dam construction, natural reproduction increased over a recent five-year period, but continues to be dependent on the variable flow-regime (Raspopov and Dubinin, 1990). Novikova (1994) estimated the capacity of the Volga spawning grounds to be 9-11,000 fish. A major problem in the 1990s was poaching. Trickey (1995), referring to Russian stocks, expected a legal harvest of 4400 tonnes with poachers taking twice that amount. This legal and illegal catch is still less than catches of 20 years ago, primarily because of pollution. Birstein (1996) records the catch of the Volga delta hatcheries in 1995 to be only 35 fish, insufficient for artificial reproduction. Natural spawners are taken by poachers. The level of poaching in the Ural River is also high, and this was the only river where some natural reproduction was going on. The fil mahi has effectively stopped reproducing in the Caspian Sea.

Moghim et al. (no date) note that juveniles of this species are caught in the beach seine fishery for other species in Mazandaran. During 2001-2002, 23,760 seine hauls had a by-catch of 6% for this species among sturgeons captured.

Khodorevskaya and Novikova (1995) point out that cooperation among all the Caspian Sea states is needed to maintain this species along with an annual release of at least 20 million young from hatcheries. Fingerlings released per year from 1998 to 2002 range from 6.9 to 12.6 million for all Caspian states (CITES website). Spawning migrations are now seen only in the Volga and Ural rivers, the Kura, Terek and Sulak rivers no longer supporting stocks. The Volga migration was 25,500 fish weighing 2600 t in the early 1970s but has fallen to 11,700 fish weighing 750 t. The commercial catch fell from 2000 t to 500 t. In the Volga River 96.3% of the spawning population consists of hatchery fish although the Ural River maintains a naturally reproducing stock.

Since stocks are maintained mostly by artificial rearing, this sturgeon has been proposed for inclusion in the "Red Book of the U.S.S.R." which forms the basis for measures to protect species (Pavlov et al., 1985; Mina, 1992). Stocks have been increased through rearing and natural reproduction in the Ural River, the number rising from 9.6 million in 1976 to 15.3 million in 1983, so the status of this species was then regarded as acceptable. However Lelek (1987) and Birstein (1993) list this species as vulnerable to endangered. Kiabi et al. (1999) consider this species to be endangered in the south Caspian Sea basin according to IUCN criteria as does IUCN and CITES (Vecsei et al., 2002). The U. S. Fish and Wildlife Service lists it as threatened under the U.S. Endangered Species Act as of 21 October 2004 (http://news/fws.gov/newsreleases, (dated 20 April 2004) and downloaded 22 April 2004) and the Wildlife Service has been petitioned to make it endangered (Speer et al., 2000). Endangered status would stop importation of flesh and caviar to the United States. Suspension of trade in this species from the Black Sea basin by the U.S. Fish and Wildlife Service was instituted in 2005 (Federal Register, 2005) and imports from Iran are banned for political reasons along with other sturgeons. Criteria for the various status assessments include commercial overfishing (fishermen cannot even catch the set quotas), failure of regulatory oversight, few in numbers, habitat destruction, dams preventing spawning migrations, medium range (25-75% of water bodies), absent in other water bodies in Iran, poaching, pollution, diseases due to pollution, and presence outside the Caspian Sea basin. The World Wildlife Federation (WWF) listed this species as number 4 on the top 10 most endangered species in the world (www.extravalue.com/sturgeon.shtml, downloaded 13 March 2000). The species status may be changed to Appendix I on the CITES listing, when international trade in its caviar would be banned (Vecsei et al., 2002). The export quota for this sturgeon in the Caspian Sea 2004 was reduced to 4425 kg although an illegal harvest was still substantial (www.tehrantimes.com, downloaded 14 October 2004).

Illegal fishing from 1990 onward and cessation of hatchery releases will lead to loss of the stock unless an agreement between Caspian states can be reached to protect this species.

The invasion of the ctenophore Mnemiopsis has led to declines in the kilka (Clupeonella spp.) stocks, a prime food of fil mahi (Kideys, 2002).

Caviar from Russian caught fil mahi bought in New York stores has been examined for pollutant content (Boyle, 1994). Three stores carried caviar with 3.17-3.27 parts per million of DDT plus its metabolites DDD and DDE, 410-640 parts per billion of the PCB Arclor 1254, and 2.1-2.8 parts per million selenium. These values are below the U.S. Food and Drug Administration's action levels of 5 parts per million for DDT, 2 parts per million of PCB and 10-50 parts per billion of selenium in drinking water. Nevertheless they are cause for concern.

Various studies have been carried out on the aquaculture of this valuable sturgeon in Iran. Mohseni et al., (2000) have studied effective stocking density of eggs and larvae in incubators and rearing tanks in order to maximise production and avoid various morphological deformities.

Abdolhay and Tahori (2006) give fingerling production as:-

Process/Year 2000 2001 2002 2003 2004
Female broodstock captured 32 29 29 48 16
Injected broodstock 19 14 21 30 9
Spawning rate * (%) 74 71.4 62 65 77
Fertilisation rate (%) 55 65.5 65 54 65
Survival rate in incubators (%) 62 73.4 62 32 72
Survival rate in tanks (%) 80 62 56 100 79
Stocking density in ponds (fish/ha) 82,100 51,639 51,333 52,359 65,448
Survival rate in ponds (%) 73 51.3 67 43 59
Fingerling production (x 1000) 1900 640 24,037 42 146

* Rate of response to hormone injection

Mohseni et al. (2006) studied the best stocking density for rearing juveniles less than one year old weighing 92.09 g on average and one-year-old fish weighing 918.14 g on average. Stocking densities were 1.6, 2.8 and 4.0 kg/m2 for the juveniles and 1.5, 2.5, 3.5 and 4.5 kg/m2 for the older fish. Increased density had a negative impact on growth, body weight, specific growth rate and food conversion ratio in both experiments. Higher concentrations of fishes even had malformed caudal fins and body injuries from increased contact. Recommended stocking densities were 1.5-2.0 kg/m2 for fish up to 90 g and 2.5-3.0 kg/m2 for fish over 900 g.

Cage culture of fingerlings has been carried out in Gorgan Bay starting in 1992. Cages were 3200 sq m with a depth of 2.5 m and contained 11,500 fingerlings. Over 16-17 months average weight increased from 20 g to 1365.5 g, to a maximum of 2200 g. Mean fork length was 58.6 cm. Food in the first phase was a concentrate of ground carp and kilka but in later phases natural foods such as benthos and fry were used. The preliminary results indicate economic feasibility for cage culture (Iranian Fisheries Research and Training Organization Newsletter, 7:4-5, 1995; Annual Bulletin 1993-94, Iranian Fisheries Research and Training Organization, Tehran, p. 46-47, 1995).

Kamali and Farabi (2005) showed that juveniles weighing 20 g or more adapted better to concentrated feed in fibreglass tanks. Mohseni et al. (2004) studying growth rate, food conversion ratio and survival in fingerlings held in fibreglass tanks found these factors to be dependent on higher feeding frequencies (3, 5 and 8 times per day). Akrami et al. (2005) found Cladocera were the primary prey of fingerlings in earthen ponds with chironomid larvae and ostracods secondary prey, and the copepod Cyclops an occasional prey. Condition factor and growth decreased as weight and length of fingerlings increased. Growth was was positively allometric (b>3). Mohseni et al. (2005) found growth of fil mahi was better in fibreglass tanks but later in the rearing process the trend reversed and earthen tanks showed a better condition. Mohseni et al. (2006) examined the effects of feeding rates (1, 2, 3 and 4% of biomass) on various factors for fish weighing an average 867.9 g and fed for 100 days in fibreglass tanks. Increase in feeding ratio directly increased daily food consumption and negatively affected the feeding efficiency, food conversion ratio, specific growth rate and price index. When fish were given 2% of the body weight, one unit of meat was produced from 1.92 units of food. A second trial with feeding rates 0.75, 1.5, 2.5 and 3% took place with fish weighing 2096.1 g and fed for 125 days. Feeding with 0.75% produced one unit of meat per 1.82 units of food consumed. Fatemeh and Armin (2005) studied the effect of photoperiod on growth in one-year-old fil mahi. Extended day length had a positive effect on growth rate, specific growth rate, weight and length, and condition factor. The organophosphate diazinon was studied experimentally by Khoshbavar Rostami et al. (2006) as to its effects on haematological and biochemical factors of the blood serum of this fish. Falahatkar et al. (2006) experimented with various levels of vitamin C as a diet supplement and recommended 200 mg kg-1 during the first weeks of growth and development. Mohsen et al. (2008) found that diets supplemented with L-carnitine improved growth rate, feed utilisation and stimulated protein-sparing effect. L-carnitine is a vitamin-like compound found naturally in fishes and is involved transporting long-chain fatty acids in metabolism. Ahmadifar et al. (2009) found that dietary Ergosan had some positive effects on growth and haematological parameters (Ergosan comprises algines and polysaccharides known to strengthen the full range of natural defence systems in fish).

Nezami et al. (2000) maintain that despite artificial spawning and fingerling production, restoration of this species in Iran was not very successful. Abdolhay et al. (2006) report on 17 adults caught in 1998 of which 10 fish were injected with hypophysis extract and produced 1.08 million fingerlings while in 2002, 29 were caught and 21 produced 2.4 million fingerlings. Azari Takami (1999) cites production of 300-350 kg/ha in 40 days with 106,000 fingerlings produced per 15 females in 40 days with a release weight of 10-15 g. Spawning fish were captured in the sea as they no longer migrated into Iranian rivers and propagation results were not as good as in previous years (420-587 kg/ha in 25 days, 690,000 per 2 females, release weight 5-8 g). About 1 million fingerlings were released into the Caspian Sea. Iranian releases of fingerlings were 687,400 (1988), 406,100 (1999), 1,900,919 (2000), 700,000 (2001), 2,403,794 (2002) with ca. 4 million proposed for 2003 (CITES website). The annual release of fingerlings weighing 3-5 g into the Caspian from Iran is 1-2 million fish and some of these are tagged for future studies (Iranian Fisheries Research Organization Newsletter, 39:1, 2004). In 2001, 8 females and 12-14 males were caught in Gilan, about half of which could be used as broodstock at the Shahid Beheshti hatchery (Raymakers, 2002).

Fingerlings have been raised in fibreglass ponds in brackish and fresh waters in Iran (Iranian Fisheries Research Organization Newsletter, 35:3, 2003; H. Pouralifashtomi in the 5th International Symposium on Sturgeon, Iranian Fisheries Research Organization, 9-13 May 2005, Ramsar; Pouralifashtomi, 2006). Growth was better in brackish water when fed diets containing 45% protein and 12.8% fat. Studies of cultured male fil mahi show that they attain maturity at 8-10 years, earlier than fish in natural habitats, indicative of their potential for caviar production under culture conditions (Iranian Fisheries Research Organization Newsletter, 39:3, 2004).

Cultivation of this species in earthen ponds in the central Iranian desert at Bafqh near Yazd has been carried out. After three months at 24C and a salinity of 12.5 the fish reached 250 g with a survival rate of 60%, after six months at 16C and 11.0 the fish weighed 1100 g with a survival rate of 96%. Growth was better during the cold season (Iranian Fisheries Research Organization Newsletter, 34:3; 36:4, 2003).

Further work

See under A. gueldenstaedtii.

Sources

See under family above. Babushkin (1964) gives a general review of the biology and catch of this species.

Iranian material: None.

Comparative material: CMNFI 1986-0147, 1, ca. 305 mm total length, Romania, Black Sea at Sulina (4509'N, 2941'E).

Pseudoscaphirhynchus
Nikolskii, 1900

Pseudoscaphirhynchus kaufmanni
(Kessler, 1877)

This species is reported from the Karakum Canal and Kopetdag Reservoir in Turkmenistan by Shakirova and Sukhanova (1994) and Sal'nikov (1995). It may eventually be found in the Tedzhen River and Caspian Sea basins of Iran. No Iranian record.

Clupeidae

Herrings, shads, sardines, pilchards and menhadens are moderate-sized fishes, usually less than 25 cm long, found in warmer marine waters with some species anadromous or permanent freshwater residents. There are about 56 genera and about 200 species world-wide (Nelson, 2006; Eschmeyer and Fong, 2011), with 8 species in the Caspian Sea and 1 commonly found in Persian Gulf drainages. Some other species are known to enter rivers in southern Iran (see Marine List in Checklists in Introduction). The diversity of this family in the Caspian Sea is seen in the number of subspecies which have been described, rather than in genera. At the species level there are several endemics.

Curiously, the species and subspecies in the Caspian are generally of larger size than their relatives in the Black Sea basin. These observations are attributed to the variable environment in the Caspian Sea over time, with repeated changes in salinity and temperature which the fish could not avoid. Black, Mediterranean and Atlantic species lived under more stable conditions and could, in any case, retreat from lowered temperatures for example. In addition, the Caspian Sea clupeids lacked the competitors which entered the Black Sea from the Mediterranean and Atlantic and some (Clupeonella spp., Alosa caspia) could occupy the pelagic, planktivore niche taken up by other species in the Black Sea. There are no other pelagic fish but these herrings in the stable salinity areas of the Caspian Sea.

These fishes usually have modified scales on the belly forming abdominal scutes with a saw-like edge. Most species have 2, long, rod-like postcleithra. The lateral line is usually absent or on only a few scales. Silvery cycloid scales are easily detached and are found only on the body. The mouth is usually terminal with jaws about equal in length. Teeth are small or absent but gill rakers are long and numerous for sieving plankton. Fins lack spines and there are no barbels. There is no adipose fin. The pectoral and pelvic fins have a large axillary scale. The caudal fin is deeply forked. The eye is partly covered by an adipose eyelid. The flesh is particularly oily and is highly nutritional.

Members of this family often form immense schools in surface waters of the ocean and the Caspian Sea where they feed on plankton. Schooling is an anti-predator device making it difficult for a predator to pick out an individual from a tight mass of fish. There is also a "sentry effect" where awareness is increased by the presence of many fish. The school is maintained by a balance between visual attraction and lateral line stimulus repulsion. Herring can feed on the smaller plankton, less than 300-400 m, at night by filter-feeding but during the day can also use particulate feeding. In the latter, they select larger plankton using the area temporalis, a specialised ventro-posterior region of the retina which improves vision as herring approach food items from slightly below.

Herring are easily caught and are extremely valuable to commercial fisheries. They are the most important fishes economically, both as food for man and also for many other commercial fish species. Wars have been fought over fisheries for herrings. In one year, members of the herring family made up 37.3% of all fish caught in the world. Some are used for fish meal, as fertiliser and as an oil source. The 1994-1995 catch of clupeids in the Iranian Caspian was 98.3 tonnes by beach seine and 671.5 t by gill nets, a decrease of 200 t in total over the previous year's catch (Iranian Fisheries Research and Training Organization Newsletter, 10:4-5, 1995)(but see later under Clupeonella where catch is much higher). The Caspian Sea shads account for about 35% of total inland production in Iran which was 117,300 t in 1995 (Bartley and Rana, 1998). These fish are used in a high value form as frozen whole consumer packs, as fish meal for poultry and in aquaculture, and in canning (Food and Agriculture Organization, Fisheries Department, 1996).

The catch of "sprats" (Clupeidae) in Azerbaijani waters is near extinction through poor fishery management according to Golub (1992).

Major sources for the biology and systematics of Caspian clupeids remains Svetovidov (1952), now inevitably dated but not yet updated, Whitehead (1985) and Hoestlandt (1991). There has been no recent, careful systematic and taxonomic study of these species in the Caspian Sea basin and extensive new material was not available for examination here.

Genus Alosa
Linck, 1790

The Caspian species of Alosa were formerly placed in the genus Caspialosa Berg, 1915. Svetovidov (1952) synonymised the genus Caspialosa Berg, 1915 with Alosa. There are 5 species in Iranian waters and the Caspian Sea as a whole but numerous subspecies have been described. Alosa species are also found in the Black Sea, Mediterranean Sea and Atlantic Ocean.

Often distinguished by gill raker counts which in any case overlap, the various subspecies are difficult to identify. Morphometric characters are of little help and Zamakhaev (1944) points out that some named taxa are merely different age groups. This problem is commented on further in the Species Accounts.

Caspialosa suworowi (Berg, 1913) (also spelt suvorovi in the literature) has been used for hybrids of various Caspian herrings and is not a valid species (Berg, 1948-1949). The holotype is in the Zoological Institute, St. Petersburg under ZISP 15927 (Svetovidov, 1952; Eschmeyer et al., 1996).

Alosa species are distinguished from sympatric Clupeonella species by larger size (up to 75 cm total length compared to 20 cm), a large mouth, a black spot on the flank behind the operculum and sometimes a row of such spots, an elongate scale or ala at the upper and lower base of the caudal fin, a notch at the mid-line of the upper jaw and by the last two anal fin rays not being elongated.

Caspian Sea species have a laterally compressed belly with 29-36 spiny scutes running from the throat to the anal fin; the dorsal fin origin is closer to the snout tip than the caudal fin base; the dorsal fin lies in a groove formed by enlarged scales; scales are easily detached; the pelvic fin origin lies below or slightly posterior to the dorsal fin origin; teeth are usually present on the jaws, roof of the mouth (on the palatine bone and always on the vomer bone), and on the tongue; the opercular bone is distinctly striated; eggs are demersal, semi-pelagic, and lack an oil globule; gill rakers highly variable in shape and number (18-180); dorsal fin branched rays 11-16, anal fin branched rays 10-21, scales in lateral series 49-60, and vertebrae 43-55.

Afraei Bandpyi et al. (2004) examined Alosa species from Mazandaran and Golestan provinces and found the following distinguishing characters:-

Species Gill rakers Ratio of eye diameter to total length (%)
A. braschnikowii 20-40, mean 30.9 2.9-5.8, mean 4.7
A. caspia 110-125, mean 118.3 5.7-7.5, mean 6.2
A. pontica (= kessleri) 60-73, mean 66.8 4.3-6.5, mean 5.5
A. saposchnikowii 20-48, mean 32.8 6.0-9.3, mean 7.3

The general Farsi name for these fishes is shag mahi or zalun (both in Gilaki).

These herrings migrate from the north Caspian Sea to overwinter in the central and southern parts, returning north in the spring.

Alosa braschnikowii
(Borodin, 1904)

Common names

shagmahi, shagmahi-ye Khazari.

[dolkii siyanayn, Agraxan siyanayi, Sara siyanayi, irikoz siyanak, hasangulu siyanayi, agbas siyanak, all in Azerbaijan; Caspian marine shad, Kurinskaya sel'd or Kura herring, poloschataya sel'd or striped herring, Agrakhanskaya sel'd or Agrakhan herring, bol'sheglazaya sel'd or bigeye herring, dolginskaya sel'd or dolginka herring, belogolovaya sel'd or whitehead herring, Astrabadskaya sel'd or Astrabad herring, sel'd-gonets or driver, zheltospinka or yellow-back, Gasankulinskaya sel'd or Gasan-Kuli herring, kiselevichevskaya sel'd or Kiselevitch herring, Krasnovodskaya sel'd or Krasnovodsk herring, vostochnaya sel'd or eastern herring, obzhorka or glutton, Sarinskaya sel'd or Sara herring, maiskaya sel'd or May herring, Brashnikovskaya sel'd or Brashhnikov's shad, all in Russian].

Systematics

Originally described as Clupea caspio-pontica var. Braschnikowii. Reshetnikov et al. (1997) revert to the original double "i" ending to the specific name. A lectotype from Fort Shevchenko (Aleksandrovsk) is in the Zoological Institute, St. Petersburg (ZISP 13051) and paralectotypes were designated by Svetovidov (1952)(ZISP 13051). Clupea caspio-pontica is an unneeded new name according to Eschmeyer et al. (1996).

Alosa braschnikowii is regarded as a subspecies of Alosa caspia by some authors. Clupeonella leucocephala Berg, 1913 from Sumgait and Gyurgenchai, Azerbaijan is a synonym (as Caspialosa brashnikovi leucocephalia (sic) it is listed as a synonym of C. b. grimmi in Mikhailovskaya (1941)), as is Caspialosa caspia nigra Kisselevitsh, 1923 from the Caspian Sea opposite Dzambai (the material also included specimens of Alosa saposchnikowii) (Whitehead, 1985; Eschmeyer et al., 1996).

Alosa braschnikowii has 9 subspecies in the Caspian Sea (including Alosa curensis (q.v.) the Kura or striped herring), namely agrachanica (Mikhailovskaya, 1941) (author also spelt Mikhaylovsky or Mikhailovsky; dated 1940 in Eschmeyer et al. (1996) here and below but 1941 on the paper itself and in Svetovidov (1952) and Berg (1948-1949); species also spelt agrakhanika in Berg (1948-1949); Caspialosa brashnikovi morpha elata is a synonym according to Mikhailovskaya (1941)), the Agrakhan herring; autumnalis (Berg, 1915), the bigeye herring; braschnikowii (Borodin, 1904) (also spelt brashnikovi in Svetovidov (1952) and Berg (1948-1949)), the dolginka herring; grimmi (Borodin, 1904), the whitehead or Astrabad herring, driver or yellow-back; kisselevitshi (Bulgakov, 1926) (spelt kisselevitschi on the plate in Bulgakov (1926), kisselevitschi in Mikhailovskaya (1941), kisselevitshi in Svetovidov (1952) and Whitehead (1985) and kisselewitschi in Berg (1948-1949)), the Gasan-Kuli or Kiselevitch herring; nirchi (Morosov, 1928)(author also spelt Morosow in Mikhailovskaya (1941) and Morozov in Eschmeyer et al. (1996)) (with Caspialosa brashnikovi kenderlensis Budamshin, 1938 from Kendyrli Bay as a synonym in Svetovidov (1952) and Berg (1948-1949)), the Krasnovodsk herring; orientalis (Mikhailovskaya, 1941), the eastern herring or glutton; and sarensis (Mikhailovskaya, 1941), the Sara or May herring. Caspialosa brashnikovi derzhavini Tarasevich, 1946 described from the Caspian Sea near the Apsheron Peninsula, Azerbaijan may be another subspecies. Caspialosa kiselevitschi morpha elata Morozov, 1928 from the Caspian Sea, Krasnovodsk Bay, Turkmenistan is an infrasubspecific taxon and its availability and validity as a taxon have not been examined (Eschmeyer et al., 1996).

This high number of subspecies is an indication of the populational variation of this shad and not all subspecies may be valid. A modern revision is required to assess this problem. In light of this uncertainty and the lack of adequate sample sizes to determine which of the subspecies occurs in Iranian waters or which taxa are valid, reference is made here mostly to the species level. Additionally, it should be noted that hybrids between the various subspecies, and between this species and other species, do occur to complicate matters even further.

The neotype of Caspialosa brashnikovi agrachanica was designated by Svetovidov (1952) as the specimen described by Berg as Caspialosa brashnikovi m. elata taken in front of the Sulak River mouth, Agrakhan Bay and housed in the Zoological Institute. St. Petersburg under ZISP 7334. However, this neotype was not validly designated because qualifying conditions 75.3.1, 75.3.4 and 75.3.5 of the International Code on Zoological Nomenclature were not met (N. G. Bogutskaya, pers. comm., 23 January 2013). This also applies to the following 6 taxa.

The neotype of Caspialosa braschnikowi autumnalis was designated by Svetovidov (1952) as a specimen 26.9 cm long from the eastern shore of the Caspian Sea at Gasan-Kuli (just north of the Iranian border in Turkmenistan) caught on 8 April 1948 and housed under ZISP 31749.

The neotype of Caspialosa kisselevitshi is also from Gasan-Kuli caught on 30 June-1 July 1926 and was housed in the Faculty of Zoology, Central-Asian State University (Sredne-Aziatskogo Gosudarstvennogo Universiteta), Tashkent.

The neotype of Clupea caspio-pontica var. grimmi was designated by Svetovidov (1952) as a specimen 34.0 cm long found at Ashur-ade (= Ashuradeh) near Astrabad Bay (= Gorgan Bay or Khalij-e Gorgan) on 23 April 1903 is under ZISP 13045.

The neotype of Caspialosa nirchi as designated by Svetovidov (1952) is from the southern part of the Caspian Sea opposite North Cheleken Spit and is under ZISP 31780.

The neotype of Caspialosa brashnikovi orientalis as designated by Svetovidov (1952) is from the southern part of the Caspian Sea opposite Kara-Ashly and is under ZISP 32187.

The neotype of Caspialosa brashnikovi sarensis from Sara Island is under ZISP 32184 as established by Svetovidov (1952).

The lectotype of Clupea curensis from the Kura River estuary is under ZISP 13984 with many paralectotypes as established by Svetovidov (1952) (Eschmeyer et al., 1996).

Key characters

Characterised by a relatively elongate and rounded body likened to a "herring" shape, not as deep as in some related species which are likened to a "shad" shape. Total gill rakers 18-49 and short (about equal to gill filaments in length, sometimes shorter). Teeth are well developed in both jaws.

Morphology

Dorsal fin with 3-5 unbranched and 12-15, mostly 14, branched rays, anal fin with 2-4, usually 3, unbranched rays and 10-20, mostly 18, branched rays. Scales in lateral series 51-54. Teeth are well-developed on the jaws, tongue and roof of the mouth.

The accompanying table summarises characters of the subspecies and is taken from Svetovidov (1952) and Mikhailovskaya (1941) but identification to subspecies should be done with the keys from these works. Some of the characters used in the keys are not in the table as they do show individual variation and are difficult to summarise. An example is the nature of the gill raker (thin, thick, blunt, pointed, bent, straight, curved, branched, broken off, forked, swollen at the tip, etc.); another is the degree of protrusion of the lower jaw.

The subspecies grimmi is quite specialised in association with its benthic mode of life, feeding mostly on gobies (Gobiidae). It has a unique character in the well-developed callus on the tip of the lower jaw which adults acquire from rubbing the jaw on the sea bed while feeding, gill rakers are low in number as fine food is not taken, and the tips are broken off, broadened, and split owing to abrasion, and the rakers on the lower arch are reduced in number so the first raker is far from the tongue base. The subspecies nirchi is similar. In contrast, the subspecies kisselevitshi has a high gill raker count, rakers are pointed and not split at the tips, and the first raker is close to the tongue base. This species lives in surface waters feeding on Clupeonella, Atherina, shrimps, gammarids, and gobies (Gobiidae).

Character / Subspecies

Gill rakers (mostly)

Pectoral fins as % body length

Vertebrae

Head length as % of body length

agrachanica

20-46 (28-33)

13.1-15.6

47-54

22.6-25.2
autumnalis

21-37 (28-30)

16.4-19.9

45-53

26.0-29.2

braschnikowii

24-47 (30-33)

14.3-16.7

48-55

23.5-26.6
curensis

26-54

17.3-18.8

47-52

25.7-26.5

grimmi

18-28 (20-22)

12.9-15.2

45-52

22.9-26.4

kisselevitshi

29-49 (36-40)

13.9-16.8

43-53

24.2-26.9

nirchi

20-31 (23-26)

10.9-14.7

48-52

23.4-26.3

orientalis

20-35 (27-32)

13.5-18.0

45-53

25.0-27.8

sarensis

20-33 (24-27)

14.1-16.2

45-53

23.8-26.6

Sexual dimorphism

None reported.

Colour

The back and top of the head are dark with a green or blue tint and may be grey-green. Some subspecies are paler in colour with a grey or grass-green back and pale flanks, nirchi has a whitish blue-green head, light grey back with a slight greenish tint, and lower jaw and pectoral fins light, while grimmi is also quite pale with a grey-blue back and top of the head and whitish anterior head and pectoral fins. There is a dark spot behind the operculum but no series of spots along the flank in most subspecies, except in rare cases when there may be up to 7, occasionally 12-13. The subspecies grimmi regularly has a row of diffused, grey spots almost merging into a stripe, and nirchi occasionally. Pectoral fins are dark on some subspecies (braschnikowii, sarensis, kisselevitshi), pale or whitish on the others, although there is confusion in the literature over this, perhaps indicative of individual variation (cf. sarensis in Mikhailovskaya (1941)). The back and upper part of the head may become a deep black at spawning. The flanks and belly are silvery.

Size

Attains 50 cm standard length but average lengths are about 27-34 cm.

Distribution

All the Caspian subspecies are found widely distributed in the sea but chiefly in the south in winter, moving north to spawn in spring. The subspecies sarensis is reported from the Lenkoran coast and from southwest of Gasan-Kuli (in Turkmenistan just north of the Iranian border), the subspecies orientalis from Gorgan or Astrabad Bay, autumnalis from coastal waters at Gasan-Kuli, kisselevitshi from Astara and Gasan-Kuli, and grimmi from Astara and Gorgan Bay.

Zoogeography

This species is endemic to the Caspian Sea.

Habitat

In winter this species moves into deeper water towards the Iranian coast. In March it approaches coastal waters (Vetchanin, 1984) including brackish waters but does not enter fresh water. It never enters rivers in the south of the Caspian Sea (Jolodar and Abdoli, 2004). Salinities up to 47.6 are survived by this species. Spawning and feeding grounds are in the north Caspian for some populations but others live permanently in the south Caspian Sea and are of smaller size. The subspecies kisselevitshi, for example, lives off Gasan-Kuli in winter at depths below 25 m, not migrating or feeding. In March they move north to feed and then return south to spawn but lives almost entirely as a pelagic species in the southern Caspian Sea. Knipovich (1921) reports this species from depths of 80-98 m in Iranian waters. The density of this species increased from east to west in a 1999-2001 study in Iranian waters (Afraei, 2006). Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea in Iranian waters.

Age and growth

Maturity is attained at age 2-5 and life span is up to 10 years, although this varies with the subspecies. Most south Caspian forms apparently mature at age 2 according to Svetovidov (1952). Growth rates also vary between subspecies, orientalis being one of the slowest growing herrings in the Caspian Sea and reaching 10 years of age. The catch near Astara of sarensis, for example, is mainly 4-5 year olds but this too varies with the subspecies and also with the year-class strength. Vetchanin (1992) reported on grimmi catches from the southeastern Caspian where the average length was 27.8-28.6 cm and the average weight 294-313 g. There is a tendency for length and weight to fall in catches as the summer progressed, from April to July. Length and weight are less in southern, compared to northern, waters. Afraei (2000) found this species to be the largest Alosa in Iranian waters on average at 395 mm and 760.3 g. Males predominate at 55.8% in Mazandaran and 69.4% in Golestan catches. Six age classes were present (1+ to 6+) with the 2+ class being the most common at 28.9% and 6+ the rarest at 8.9%.

Food

Diet in the southeastern Caspian Sea in winter comprises 85% Clupeonella engrauliformis with some gobies (Neogobius) and shrimps (Vetchanin, 1984). From March to November the diet is dominated by Clupeonella caspia, Atherina boyeri (= caspia) and shrimps. Juvenile Liza saliens, Syngnathus caspius, molluscs, crabs and higher aquatic plants are also recorded along with foreign objects such as rice husks, pieces of wood, foil, polyethylene, etc. This species is a cannibal. The more southerly populations examined favour Atherina boyeri (= caspia) and Neogobius species and some of these populations favour benthic invertebrates. The subspecies grimmi is the most benthic one and takes primarily gobies with some molluscs as well as Clupeonella. Feeding intensity rises sharply after spawning. While some herrings, like Alosa pontica (= kessleri), feed poorly on their migration, this species feeds intensively on its spring migration.

The feeding regime altered after the invasion of the ctenophore, Mnemiopsis leidyi. A shift was observed from 85% Clupeonella engrauliformis to 65% Atherina boyeri (= caspia). Other fishes were also eaten including Clupeonella grimmi, C. caspia, Cyprinus carpio, Liza saliens, as well as Palaemon spp. (Iranian Fisheries Research Organization Newsletter, 49:2, 2006).

Reproduction

Vetchanin (1984) reports spawning of this species in the southeastern Caspian Sea north of Iranian waters to begin in early May, continuing to July as it is intermittent. The subspecies sarensis spawns along the Lenkoran coast from mid-April to the end of June. The subspecies orientalis spawns in Gorgan Bay from the end of March to the beginning of April, spawning schools forming at 17-18C or higher. The subspecies autumnalis spawns at the same time off Gasan-Kuli near the Iranian border with Turkmenistan. The subspecies grimmi spawns in May-June in Gorgan Bay. The subspecies kisselevitshi has the latest spawning date, June to July and even in August off Gasan-Kuli when temperatures exceed 25C. Spawning takes place in shallow water (1.8-5.8 m) in the sea over sand or silt bottoms at 15-18C (some subspecies and populations at 20-22C, others beginning as low as 11C), and a salinity of 8-13. Fecundity is up to 178,400 eggs, average 66,000 per fish. There is no feeding while spawning. Early maturers, like the south Caspian populations, can reproduce up to 7 times in their life.

Parasites and predators

The Caspian seal, Pusa caspica, is a predator on this species (Krylov, 1984).

Economic importance

The catch for all species of "Caspialosa" in Iran varied between 5337 kg and 419,518 kg for the years 1956/1957 to 1961/1962 (Vladykov, 1964). In the Anzali region the catch for the years 1933/1934 to 1961/1962 varied from 1553 kg to 539,710 kg (Vladykov, 1964).

The catch has been as high as 126,900 centners or 12,690 t in the sea as a whole for the type subspecies alone (1 centner = 100 kg (Svetovidov, 1952)), taken chiefly in spring. Other subspecies were not fished for as extensively although kisselevitshi was the most numerous of the south Caspian forms of Alosa braschnikowii, forming 70% of the drift net catch.

Conservation

Reputedly depleted in Iranian waters. Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include medium numbers, medium range (25-75% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin. Extinct in Turkey (Fricke et al., 2007).

Further work

The biology of this species in Iranian waters and the stocks or taxa found there need to be elucidated.

Sources

Iranian material: CMNFI 1970-0581, 5, 226.0-245.0 mm standard length, Gilan, Caspian Sea near Hasan Kiadeh (3724'N, 4958'E); CMNFI 1979-0431, 1, 297.2 mm standard length, Mazandaran, bazaar at Now Shahr (no other locality data); CMNFI 1980-0126, 1, 245.8 mm standard length Gilan, Caspian Sea near Bandar-e Anzali (3728'N, 4927'E); CMNFI 1980-0150, 1, 222.4 mm standard length, Gilan, Safid River estuary (3724'N, 4958'E).

Comparative material: BM(NH) 1938.8.2:1, 1, 245.9 mm standard length, Kazakhstan, Caspian Sea, Kaidak Bay (no other locality data); BM(NH) 1938.8.2:2, 1, ca. 337.5 mm standard length, Kazakhstan, Caspian Sea, Kaidak Bay (no other locality data); BM(NH) 1939.2.21:17-18, 2, 285.0-305.2 mm standard length, Caspian Sea (no other locality data); BM(NH) 1939.2.21:19-20, 2, 222.9-273.4 mm standard length, Caspian Sea (no other locality data).

Alosa caspia
(Eichwald, 1838)

Common names

shagmahi-ye shekambozorg (= big belly herring fish), shagmahi-ye chekameh dar, shagmahi-ye darya-ye khazar (= Caspian Sea herring fish), شاه ماهي (= shah mahi, meaning king fish), zalun (in Gilaki), puzanok.

[xazar sisgarini, sara sisgarini in Azerbaijan; Kaspiiskii puzanok or Caspian shad, severokaspiiskii puzanok or North Caspian shad, srednekaspiiskii puzanok or Central Caspian shad, il'mennyi puzanok or il'men shad, Enzeliiskii puzanok or Enzeli (= Anzali) shad, Sarinskii puzanok or Sara shad, Bakinskii puzanok or Baku shad, Astrabadskii puzanok or Astrabad shad, all in Russian].

Systematics

Clupea caspia was originally described in Latin from "Hab. in Caspio mari, meridiem versus" (Caspian Sea, towards the south).

A. caspia has 3 subspecies in the Caspian Sea basin, namely caspia (Eichwald, 1838) (= North Caspian, Central Caspian, Caspian or il'men shad); knipowitschi (Iljin, 1927) with natio knipowitschi (Iljin, 1927) (= Enzeli or Anzali shad) and natio saraica (Svetovidov, 1943) (= Sara or Baku shad); and persica (Iljin, 1927) (= Astrabad shad). The differences between natio knipowitschi and natio saraica are small (e.g. gill rakers 122-166 versus 140-150, both averaging 145; vertebrae 43-49 versus 45-51, both with mostly 47 or 48; growth differences are known, the former grows faster in the first 2 years of life but the latter reaches a greater size) and they probably have no taxonomic significance being simply separate breeding populations. The differences between Alosa caspia caspia natio caspia (the North or Central Caspian shad) and natio aestuarina Berg, 1932 (the il'men shad) were found to be based on geography and growth rate and these names have no taxonomic standing (Svetovidov, 1952). These natio are infrasubspecific ranks and have no validity as names.

Alosa rossica Kessler, 1870 described from the Volga River is a nomen nudum and is this species. Other taxa now considered as synonyms of Alosa caspia are Caspialosa caspia salina Svetovidov, 1936 from Mertvyi Kultuk and Kaidak bays in the northeast Caspian Sea and Caspialosa caspia kaidakensis Kazancheev, 1936 (spelt kajdakensis in Svetovidov (1952)) from Kaidak, the latter being in any case a synonym of the former subspecies. Clupeonella caspia m. elongata Berg, 1913 is also a synonym. Alosa caspica Yakovlev, 1871 is presumably a misspelling.

Knipovich (1921) records a species, Caspialosa enzeliensis Iljin, from the southern Caspian Sea which he places as a subspecies of caspia. I have been unable to locate the original description of this taxon, which presumably is found in the Anzali Mordab of Iran. It is probably an unused manuscript name for what Iljin later described as knipowitschi. As of 15 July 2007, this scientific name is a Googleblat for this page.

The lectotype of Caspialosa knipowitschi is a specimen 21.2 cm long from Anzali in Iran caught on 15 April 1915 and housed in the Zoological Institute, St. Petersburg (ZISP 31892). The lectotype of Caspialosa caspia var. persica is a specimen 147.5 mm long from the Caspian Sea Bay of Asterabad (= Gorgan Bay or Khalij-e Gorgan) north of Ashur-ade (= Ashuradeh) at 3653'N, 5355'E caught on 25 April 1904 on the Caspian Expedition of 1904 and housed in the Zoological Institute, St. Petersburg (ZISP 16413). The lectotype of Caspialosa caspia knipowitschi n. saraica is from near Sara Island and is under ZISP 32183. The lectotype of Caspialosa caspia salina is from Mertvyi Kultuk Bay, 10 km west of Cape Kizil-kair and is under ZISP 25813. These taxa were designated by Svetovidov (1952) as none were before or material was not preserved.

Key characters

Characterised by a relatively deep and compressed body likened to a "shad" shape, not as elongate and rounded as in some related species which are likened to a "herring" shape. Total gill rakers 50-180, variously reported as thin or thick, long (obviously longer than the gill filaments), and forming a convex outline on the lower arch. Teeth are poorly developed in both jaws.

Morphology

Dorsal fin with 3-4 unbranched and 12-15 branched rays, anal fin with 3-4, usually 3, unbranched and 15-20 branched rays. Scales in lateral series 49-54.

The characters distinguishing subspecies all overlap widely and are given below after Svetovidov (1952) and Hoestlandt (1991):-

Characters / Subspecies Head length as % of body length Pectoral length as % of body length

Vertebrae

Gill rakers

caspia

25.5-28.1

15.5-18.1

45-52 (49-51)

68-150 (100-140)

knipowitschi

18.3-24.1*

16.0-19.1

43-51 (47-48)

120-180 (130-160)

persica

25.6-27.1

16.5-17.7

45-51 (47-49)

50-120 (60-90)

* The numbers cited in Svetovidov (1952: 256 in the English version) and Hoestlandt (1991: 128) in the keys to subspecies do not agree with the numbers on p. 148 and p. 265 respectively in the species descriptions. The text numbers are used here.

Sexual dimorphism

Females are longer and weigh more than males of the same age.

Colour

The back is blue-green to dark and the flanks silvery. There is a black spot on the flank behind the upper operculum margin and sometimes up to 7 spots extending along the upper flank to a level of the rear of the dorsal fin.

Size

Reaches 28 cm standard length for caspia, to 29.6 cm for knipowitschi, and to 33.8 cm for persica.

Distribution

Found in the Caspian and Black seas. The subspecies caspia is found mostly in the western half of the Caspian Sea basin but is the most widely distributed subspecies, found throughout almost the whole sea. The subspecies knipowitschi is found in the south near Anzali, Astara and the Baku Archipelago, near the northern shore of the Apsheron Peninsula in autumn with a few reaching the Gorgan Mordab in fall and winter; natio saraica is found north of Astara and spawns near Sara Island, natio knipowitschi spawns in the Anzali Mordab. The subspecies persica is found in the southeast, near Gorgan or Astrabad Bay. Holčk and Olh (1992) report persica from the western basin of the Anzali Mordab (= Talab) and this species is reported from the Safid River and Anzali Talab as subspecies persica and from the Anzali Talab as knipowitschi (Abbasi et al., 1999). Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea, the Anzali Talab and Gorgan Bay in Iranian waters for both knipowitschi and persica.

Zoogeography

This species is part of a marine fauna encompassing the Black and Caspian seas, surviving in the reduced salinity of the latter.

Habitat

The type subspecies prefers open waters. Caspian shad winter at depths of 30-40 m or more and prefer temperatures not less than 8-11C. They rise to surface waters in spring, moving north along the western shore of the Caspian Sea in waters of about 9-11C according to Kushnarenko (1986) while Heckman in Hoestlandt (1991) states that this shad begins to migrate at the end of March at 5-6C water temperature with a peak at 9-14C in mid to late-April, ending in early May. Males migrate in large numbers at the beginning and end of the migration, females in the middle (Pushbarnek, 1987) while Heckman in Hoestlandt (1991) states that two waves of migration occur, one usually in late April at 7.6-10.2C comprised of over 80% males and the second in the first half of May at 10.8-14.0C comprised of over 70% females. The young, which hatch in the spring, leave the summer feeding grounds before the adults and migrate south before October-November. Adults follow as temperatures fall. Some populations do not migrate north and spend their whole life in the southern Caspian Sea. This subspecies will enter fresh waters to spawn in addition to spawning in the open Caspian Sea. The subspecies knipowitschia prefers water warmer than that of all other Caspian Sea clupeids except for Alosa caspia persica. Its sea movements are not well known but spawning fish favour waters with freshwater input and some fish enter rivers so it is classified as semi-anadromous. This subspecies was common in the Anzali Mordab but is now replaced by persica (Holčk and Olh, 1992). It is also reported westwards to Astara and eastwards to Gorgan Bay. The winter habitat of persica is unknown. It is semi-anadromous and remains in the southern Caspian Sea near the shore. From spring to fall this subspecies moves northward along the eastern Caspian shore towards Krasnovodsk Bay and westwards to the Anzali Mordab.

Age and growth

Pushbarnek (1987) found shad of the type subspecies up to 7 years of age on the western coast of the middle Caspian Sea. In the spawning population, the predominant sizes and weighs for males were 16-21 cm and 60-130 g and for females 18-23 cm and 70-140 g. Males and females usually mature at 2-3 years although most spawn for the first time at 3 years. Females grow faster than males. Shad may spawn up to four times as the period of sexual maturation may continue for 2-5 years. The age composition of the spawning population is dependent on year-class strength. First spawners constitute 75.9% of 3-year-olds, 41.7% of 4-year-olds and 23.5% of 5-year-olds. The Caspian shad is a slow-growing species compared to A. braschnikowii and A. saposchnikowii, its mean length being 21.2 cm compared to 32.2 cm and 25.6 cm for the two other species respectively (Shubina, 1981).

Dmitriev (1947) briefly examined the Anzali, Iran population and found 6 age groups but life span is noted by Heckman in Hoestlandt (1991) to be up to 9 years. Maturity is attained as early as 2 years although most fish appear to mature later as most spawners are 4-5 years old. The subspecies persica is the slowest growing of the shad species in the Caspian Sea, sexually mature fish being 13-21 cm long. Some fish become mature at 2 years of age. Life span is up to 8 years. The populations of both knipowitschi and persica are small compared to caspia. Abbasi and Sabkara (2004c) studied 180 fish from the southeast Caspian Sea coast of Iran and found fork length to be 103-232 mm, mean 158.8 mm, weight 16-130 g, mean 52.2 g and age 2-5 years, mean 2.64 years. Afraei (2000) found this species to be the smallest Alosa in Iranian waters on average at 110 mm and 109 g. Patimar et al. (2011) found Iranian fish to reach age 5+ years, with positive allometric growth in the southeast Caspian, and negative allometric growth in the central and southwest Caspian. Females had  a b-value larger than males. von Bertlanffy growth functions were variable, different between males and females of each area and between sexes from different areas. The largest L was in the southeast for males and in the central area for females. The highest K value was for males and the lowest for females in the southeast area. t0 was negative in all areas with lowest value for females (-0.531) in the southeast and the highest for males (-0.145) in the central area.

Food

The most intensive feeding period occurs after reproduction, beginning in June and the highest condition factor is found at the end of this summer feeding period. Little food is eaten in winter. Temperature (affecting metabolic rate) and zooplankton biomass (decreases engender competition with Clupeonella engrauliformis and other planktivores) are important factors governing catches of this species (Shubina, 1981). Food is chiefly copepods, more than 70%, with mysids at 20%, but some phytoplankton and small fishes are taken. Food in rivers after spawning is mostly cladocerans and other crustaceans. The above refers to the type subspecies; food of the other two subspecies is assumed to be similar. The southeast Caspian Sea fish studied by Abbasi and Sabkara (2004c) fed on phytoplankton (Rhizosolenia and Sprirogyra) at 4.5%, zooplankton (Foraminifera, Copepoda, Cirripedia, Bivalvia larvae) at 95.0%, and bony fish larvae and eggs at 0.5%. The presence of the ctenophore, Mnemiopsis leidyi, a food competitor reduced the index of fullness and fish growth was reduced. Abdollapour Bereya et al. (2007) studied diet in fish from beach seines and gill nets in Gilan. 98.0% of the stomach contents were zooplankton (ostracods, rhizopods, cladocerans, rotatarians, copepods, cirripedes, mysids, bivalve larvae and bony fish larvae and eggs), 1.8% was phytoplankton (notably Rhizosolenia and Spirogyra), and 0.2% was benhthic items (foraminiferans, sponges, cumaceans, amphipods, insect lavae and palaemonids). Acartia spp. (copepods) at 83.1% and Balanus (cypris larvae of the cirripede) at 12.9% were the most abundant. The zooplankton have declined drastically from predation by Mnemiopsis leidyi, the invasive ctenophore, and the fish have shown a great reduction in the index of fullness and in growth recently.

Reproduction

Most spawning of the type subspecies occurs in the north Caspian Sea near the outflow of the major rivers, particularly the Volga, and the fish overwinter in the south Caspian, migrating between the two areas (Shubina, 1981). This subspecies spawns successively, 3 times within a week. Some fish enter fresh water to spawn. Spawning takes place at the favoured water temperature of 13.8-24.1C, with mass spawning at 18-22C, beginning as early as late April or as late as mid-May and continuing to mid- or late June. Most eggs are released in the upper 3 m of the water column. Fecundity reaches 41,000 eggs. The eggs are 1.11-1.38 mm when ripe but unfertilised and 1.92-2.91 mm in diameter when fertilised and are semi-pelagic to demersal. The subspecies knipowitschi spawns in the Anzali Mordab (and probably the "Chemkhala" River to the east of the Safid River) in May and June after a spring migration from the sea, leaving in the fall. Spawning of the subspecies persica takes place in Gorgan Bay and Holčk and Olh (1992) suspect from catches of mature and spent fish that it also occurs in the Anzali Mordab.

Parasites and predators

The Caspian seal, Pusa caspica, is a predator on this species (Krylov, 1984) and it forms a substantial part of the diet of Silurus glanis in the Anzali Mordab (Holčk and Olh, 1992). Ashoori et al. (2012) found that grey herons (Ardea cinerea) in the Siahkeshim Protected Area of the Anzali Wetland ate this species.

Naem et al. (2002) found the monogenean trematode Mazocraes alosae on the gills of this species in the western branch of the Safid River. Barzegar et al. (2008) record the digenean eye parasite Diplostomum spathaceum from this fish. Youssefi et al. (2011) report the digenean Pronoprymna ventricosa from fish in the Babol River. Barzegar et al. (2012) found Mazocraes alosae, Diplostomum spathaceum (monogeneans), Pronoprymna ventricosa (digenean), and Hysterothylacium sp. (anisakid).

Economic importance

The type subspecies was the most important subspecies in the herring family in the Caspian Sea. It is caught off the coasts of Dagestan and Azerbaijan for research purposes and comprises 85% of the clupeid catch (Pushbarnek, 1987), 80-90% of the Caspian commercial catch (Kushnarenko, 1986). During the 1970s it was only 2% of the total Caspian fishery production. These herrings dominated the commercial catch in the Caspian Sea until the 1960s when commercial fishing was banned except on the western coast of the central Caspian. Many young of other commercial species were being killed in the herring fishery, entangled in the gill nets used. Soviet catches have weighed as much as 75,000 t. This fish is fattier than other Caspian Clupeidae, except for Alosa kessleri, up to 18.1% of the body weight. The fat content decreases on the spring migration. The catch of the subspecies knipowitschi is of minor economic importance and had been little exploited when Svetovidov (1952) summarised biology, as the age of captured fish indicated. About 420 tons (sic, possibly tonnes) were caught in the Anzali Mordab in 1933 and 1934, but this may be an error in the report by Vladykov (1964) according to Holčk and Olh (1992) although Berg (1948-1949) reports 4200 centners for the same period. The fishing season in the mordab began in mid-April and ended in mid-June when spent fish appeared. There appears to be no fishery data on the subspecies persica in the sea. Holčk and Olh (1992) report catches of persica, which replaced knipowitschi, in the Anzali Mordab from the end of April to the beginning of June but in 1990 this comprised only 5 kg. It is regarded as of inferior quality in Iran. The Caspian shad is the dominant fish catch in the Iranian Caspian, comprising 51,000 t in 1994 rising from nothing a decade earlier (Food and Agriculture Organization, Fisheries Department, 1996). Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food.

Conservation

The stocks of this species in the Anzali Mordab are likely to increase as the lagoon becomes more saline (Holčk and Olh, 1992). Kiabi et al. (1999) consider this species to be of least concern in the south Caspian Sea basin according to IUCN criteria. Criteria include abundant in numbers, widespread range (75% of water bodies), absent in other water bodies in Iran, and absent outside the Caspian Sea basin. Extinct in Turkey (Fricke et al., 2007).

Further work

The biology of this species in Iranian waters and the stocks or taxa found there need to be elucidated.

Sources

See under family heading.

Iranian material: CMNFI 1970-0524, 11, 58.7-88.9 mm standard length, Gilan, Caspian Sea at Bandar-e Anzali (3728'N, 4927'E); CMNFI 1970-0532, 1, 113.0 mm standard length, Gilan, Caspian Sea near Bandar-e Anzali (3728'N, 4927'E); CMNFI 1970-0543A, 1, 85.9 mm standard length, Gilan, Caspian Sea at Hasan Kiadeh (3724'N, 4958'E); CMNFI 1970-0586, 1, 77.5 mm standard length, Mazandaran, Gorgan Mordab at Ashuradeh-ye Kuchak (3650'N, 5356'E); CMNFI 1970-0587, 2, 107.4-108.6 mm standard length, Mazandaran, Babol Sar (3643'N, 5239'E); CMNFI 1971-0343, 1, 95.5 mm standard length, Gilan, Langarud at Chamkhaleh (3713'N, 5016'E); CMNFI 1979-0430, 1, 118.0 mm standard length, Mazandaran, river east of Now Shahr (3639'N, 5131'E); CMNFI 1979-0431, 7, 120.8-155.1 mm standard length, Mazandaran, Now Shahr bazaar (no other locality data); CMNFI 1979-0686, 2, 119.7-126.9 mm standard length, Gilan, Safid River (3724'N, 4958'E); CMNFI 1980-0146, 2, 106.9-171.8 mm standard length, Mazandaran, Gorgan Mordab at Ashuradeh-ye Kuchak (3650'N, 5356'E).

Comparative material: BM(NH) 1938.8.2:3, 1, 203.8 mm standard length, Caspian Sea (no other locality data); BM(NH) 1939.2.21:22-23, 2, 175.6-179.2 mm standard length, Caspian Sea (no other locality data); BM(NH) 1954.6.24:5-7, 3, 164.1-189.1 mm standard length, Caspian Sea (no other locality data).

Alosa curensis
(Suvorov, 1907)

This species is poorly known and not recorded from Iran but from Kyzylagach Bay of Azerbaijan. It may, in any case, be a subspecies or synonym of Alosa braschnikowii (see Svetovidov (1952) and the Alosa braschnikowii account herein).

Alosa kessleri
(Grimm, 1887)

Common names

shagmahi-ye poshtsiah, shagmahi darya-ye siah, shagmahi-ye moohajer or shagmahi-e-mohajer, zalun (in Gilaki), puzanok.

[Volga siyanayi, garabel siyanak in Azerbaijanian; arkasy gara takgas in Turkmenian; blackback, Caspian anadromous shad; chernospinka or black-spined herring, chernonosik or blacknose, beshenka, zalom, poluzalom, zheleznitsa, veselka, Volzhskaya mnogotychinkovaya sel'd or Volga many-rakered herring, Volzhskaya sel'd or Volga herring, Astrakhanskaya sel'd or Astrakhan herring, all in Russian; Pontic shad, Black Sea herring].

Systematics

Clupea kessleri was originally described from the Volga River delta, Astrakhan. Clupea pontica was originally described in Latin from "Hab. in Ponte Euxino prope Odessam" (= Black Sea near Odessa).

Alosa kessleri was formerly considered as a subspecies of A. pontica. Alosa pontica then had two subspecies in the Caspian Sea, namely kessleri (Grimm, 1887) (chernospinka or black-spined herring, chernonosik or blacknose, beshenka, zalom, poluzalom, zheleznitsa, veselka, blackback), and volgensis (Berg, 1913) (Volzhskaya mnogotychinkovaya sel'd or Volga many-rakered herring, Volzhskaya sel'd or Volga herring, Astrakhanskaya sel'd or Astrakhan herring, zheleznitsa, beshenka, veselka).  Kottelat and Freyhof (2007), Abdoli and Naderi (2009) and Naseka and Bogutskaya (2009) consider Alosa kessleri and A. volgensis to be valid species.

A lectotype of kessleri, 40.1 cm long, was designated from the Volga Delta by L. S. Berg under ZISP 15925 (in the Zoological Institute, St. Petersburg). A lectotype of volgensis, 34.8 cm long, is under ZISP 15926 and is from the Volga River at Chernyi Yar (Svetovidov, 1952). A paralectotype of kessleri is under ZIN 15922.

Caspialosa volgensis bergi Tanasiichuk, 1938 described from the Volga Delta is a synonym of Alosa kessleri (Heckman in Hoestlandt, 1991). Eschmeyer et al. (1996) give author and date for Alosa volgensis bergi as Tanassiychuk, 1940, the variation probably being due to transliteration of a Russian name and to year of actual publication rather than year on the journal.

Caspialosa kessleri infraspecies volgensis imitans Berg, 1948 from the Caspian Sea (see Berg (1948-1949) for further details) is not available because of its infrasubspecific rank (Eschmeyer et al., 1996).

Clupea caspio-pontica Borodin, 1904 is an unneeded new name for these fishes from the Black and Caspian seas (Eschmeyer et al., 1996).

Key characters

Characterised by a relatively elongate and rounded body likened to a "herring" shape, not as deep and compressed as in some related species which are likened to a "shad" shape. Total gill rakers 57-158 in the Caspian Sea, 57-95 in kessleri, 87-158 in volgensis. Rakers are usually longer than the gill filaments in volgensis, shorter in adult kessleri. Teeth are well developed in both jaws in kessleri and can be felt with a finger, poorly developed in volgensis such that they sometimes cannot be felt.

Morphology

Dorsal fin with 3-5 unbranched and 12-16 branched rays, anal fin with 2-4, usually 3, unbranched and 15-21 branched rays. Vertebrae 47-50 in kessleri (also a report of 50-54, both in Svetovidov (1952)), 48-54 in volgensis. Pyloric caeca 21-62. Scales in lateral series 53-56. Gill rakers in adults are thick and often broken off at the tip or near the base in kessleri, unbroken in volgensis. The tips of the gill rakers may be swollen and they are arranged in a straight line. Young fish have long and thin gill rakers with strong lateral spines. Spines are lost with age. Chromosome number is 2n=48 (Klinkhardt et al., 1995).

Sexual dimorphism

None reported.

Colour

The overall coloration is dark with a black back which has a violet tinge in spring in kessleri, light olive green in volgensis. There is dark, sometimes vague, spot on the flank behind the operculum and sometimes a series of spots in kessleri, but these are absent in volgensis. The pectoral fin is black on top. Spawning kessleri become grey or grey-green on the back and flanks with bronze spots on the operculum and flanks. A greenish-yellow circle forms around the eye after spawning.

Size

Reaches 52 cm total length and 2.0 kg for kessleri, 40 cm for volgensis.

Distribution

Found in the Black and Caspian seas and throughout the latter, entering northern rivers to spawn. Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea in Iranian waters.

Zoogeography

This species is part of a marine fauna encompassing the Black and Caspian seas, surviving in the reduced salinity of the latter.

Habitat

Both subspecies are found in the open sea but kessleri ascends rivers much higher than volgensis which spawns in the delta region. Both subspecies overwinter in the southern Caspian Sea off the Iranian coast and then migrate north to enter the Volga and other northern rivers to spawn. The subspecies volgensis is absent from the southern Caspian in summer. The subspecies kessleri shows a greater affinity than volgensis for cold water.

The subspecies kessleri begins to migrate northward in March and April mostly along the western shore of the Caspian Sea, beginning to arrive in northern waters when temperatures are still below 5C, most arriving when temperatures are 6-8C compared to 10-13C for volgensis. A mass migration into the lower Volga takes place in late April or early May for both subspecies when water temperature reaches 9C and the peak run begins at 12-15C, ending at 22C. The run of volgensis is about 10 days later than that of kessleri and spawning takes place earlier as they do not travel as far upriver. Speed is up to 70 km/day for kessleri and depends on temperature. This fish used to run 2000 km up the Volga River. Sexually immature fish remain in the south and do not migrate. Knipovich (1921) reports kessleri as deep as 235-300 m in Iranian waters. Temperatures up to 25C are tolerated.

Age and growth

Males are sexually mature at 3 years and females at 4 years, other reports give 4-5 years for both sexes in kessleri. Many fish die after spawning but some survive to spawn two or three times. Four and five-year- olds dominate on kessleri spawning runs with some older fish also present. Females predominate in older fish making the spawning run. Life span is between 7 and 8 years.

Growth of the volgensis subspecies is slower than in kessleri, which apparently grows faster than any other Caspian clupeid. Life span in volgensis is 7-8 years with females living longer than males. Most spawners are 3-4 years old although in some years 5 year old fish are abundant. Males may mature at 2 years, females later. Most fish spawn again the next year after their first time but some may miss a year. An individual may spawn up to four times during its life.

Yılmaz and Polat (2002) compared scales, vertebrae, otoliths, opercles and subopercles as ageing structures and determined vertebrae to be the most accurate and reliable for a Turkish Black Sea population at Samsun. Six age classes were found.

Food

Cladocerans are the main food item of young kessleri which have a feeding peak at 1800-2200 hours and another at about 0800 hours. Adults in the sea take fishes such as Clupeonella and Atherina with some crustaceans and insect larvae. Clupeonella caspia makes up 92% of the diet of kessleri in the northern Caspian in May, with Sander lucioperca at 6.6% and gammarids at 1.0%. There is said to be little feeding on the spawning run although some fish sampled contained cladocerans, copepods, insects, bryozoans and fish fry.

The food of volgensis is similar to the other subspecies, taking copepods when young and larger items with growth. The main items are copepods, mysids, cumaceans, amphipods and small fishes. This subspecies feeds on the spawning migration.

Reproduction

Spawning in kessleri occurs in rivers from mid-May to mid-August, either the delta or lower reaches when entering in a ripe condition, or as much as 500 km upriver when entering in an unripe condition. Larger fish have spawning grounds further upriver than smaller fish and predominate earlier in the run. The spawning grounds in the Volga River cover a considerable stretch. Spawning usually occurs at 18-20C between 0300 and 0600 hours or from 1600 hours to sunset. Spawning occurs in the main channel, over shallow sand banks, or in backwaters. Batches of eggs are laid at intervals of several days. Eggs are pelagic as in other Caspian Alosa and develop as they drift downriver near the bottom. At 22.7C incubation takes about 40 hours. The young fish descend in late summer and early fall. Fecundity in kessleri reaches 344,000 eggs and egg diameter 1.51 mm. Shed eggs are up to 4.1m in diameter. Some fish may return to spawn in total three times.

Spawning of the first batch of eggs in volgensis may occur in the sea with the subsequent 2 batches at 7-10 day intervals in the delta and river. This takes place from mid-May to the beginning of August. Up to 281,000 eggs are shed. Peak spawning occurs at 15-19C and ends at 25-27C. Most spawning takes place in the evening between the 1600 and 2200 hours. The young appear in the pre-estuarine area of the Volga River in July and towards October begin to migrate south.

Parasites and predators

The Caspian seal, Pusa caspica, is a predator on this species (Krylov, 1984), larval shad are fed on by other fishes and by various invertebrates, and adults by various fishes and birds.

Economic importance

The subspecies kessleri and volgensis were caught on the spawning run with as much as 5750 t being taken annually pre-World War II. It is the biggest shad in the Caspian Sea. The subspecies kessleri was the most important and valuable herring in the Caspian Sea. Early spring catches were mostly kessleri but as the run of volgensis built up it formed an increasingly significant part of the catch, forming as much as 92% of the total. The catch of volgensis has declined from this period until the 1970s when the fish taken were mostly kessleri. The catch of Alosa pontica (= kessleri) on the North Caspian fishing grounds in 1965-1972 has declined to 2-4% of the 1938-1943 catch. The subspecies volgensis was one of the most important Caspian herrings, 23-29% of the total catch from 1936-1939, as high as 69,100 t in 1939.

The subspecies kessleri is said to be the tastiest Caspian clupeid because of its high fat content, averaging 18.9% of weight along the coast of Azerbaijan, while in volgensis it was 9.6%. Post-spawners of kessleri may have a fat content as low as 0.5%. Catches are processed as canned, salted and pickled fish. Beach seines are used to catch this fish. Akhondzadeh Basteh et al. (2006) found the bacterial pathogen Vibrio haemolyticus in fresh and smoked Alosa kessleri. Tavakoli et al. (2012) found a frequent contamination rate with Staphylococcus aureus and Vibrio parahaemolyticus, human pathogens, in fresh and smoked shad and they may cause health problems.

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food.

Conservation

Stocks in Iranian waters are said to be depleted. The subspecies volgensis was in Category I on the "Red List" of the Russian Republic (Pavlov et al., 1985). Kiabi et al. (1999) consider this species (as A. kessleri) to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, numbers unknown, range unknown absent in other water bodies in Iran, absent outside the Caspian Sea basin.

Further work

Stocks in Iranian waters need to be assessed and protected if required.

Sources

See under family account.

Iranian material: None available.

Comparative material: BM(NH) 1879.11.14:22-23, 2, 255.9-259.1 mm standard length, Caspian Sea (no other locality data); BM(NH) 1939.2.21:21, 1, 388.6 mm standard length, Caspian Sea (no other locality data).

Alosa saposchnikowii
(Grimm, 1887)

Common names

shagmahi-ye cheshmdorosht, shagmahi, kilka (incorrectly), herring.

[irikoz sisgarin in Azerbaijan; bol'sheglazyi puzanok or bigeye shad, Sapozhnikovskii puzanok or Saposhnikovi shad, all in Russian].

Systematics

The lectotype of Clupea saposchnikowii from the Volga Delta is in the Zoological Institute, St. Petersburg under ZISP 15921 (Berg, 1948-1949; Eschmeyer et al., 1996). The name is often spelt saposchnikovi, in error, or with a single terminal "i"; Reshetnikov et al. (1997) revert to the original spelling of the specific name.

Caspialosa caspia nigra Kisselevitsh, 1923, in part, from the Caspian Sea opposite Dzambai is a synonym with a lectotype in the Zoological Institute, St. Petersburg (ZISP 15938) (Kisselevitsh is also transliterated Kiselevich and Kisselevitz). The material also included specimens of Alosa braschnikowii (Whitehead, 1985; Eschmeyer et al., 1996).

Key characters

Characterised by a relatively deep and compressed body likened to a "shad" shape, not as elongate and rounded as in some related species which are likened to a "herring" shape. The upper and lower head profiles are straight. The upper edge of the lower jaw is straight. Total gill rakers 24-41, short (obviously shorter than the gill filaments), and thick. Teeth are well developed in both jaws.

Morphology

Dorsal fin with 3-5, usually 4, unbranched rays and 12-15, mostly 13, branched rays, anal fin with 2-4, usually 3, unbranched rays and 15-21, mostly 18, branched rays. Lateral series scales 52-55. Vertebrae 47-53. Pyloric caeca 36-59.

Sexual dimorphism

None reported.

Colour

Fish from the southern Caspian Sea are more intensively coloured than those from the north. The back is violet with green sheen, the flank has 4 dark stripes which merge with the dark on the back. There is a spot posterior to the operculum, which may be absent, and there is no series of spots.

Size

Reaches 36 cm total length and 650 g.

Distribution

Found mainly in the north Caspian Sea and the coast of Dagestan but entering Iranian waters. Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea in Iranian waters.

Zoogeography

This species is endemic to the Caspian Sea.

Habitat

This species spends its whole life in the Caspian Sea and never enters rivers. It favours colder water and is one of the first clupeid species to migrate north in spring, principally along the western coast. Large fish migrate first. Fish first approach the shore of Azerbaijan in mid-March with a mass approach from late March to mid-April. It is less frequently encountered in the southern part of the Caspian Sea, overwintering in the central Caspian and only moving south if winters are cold. A Caspian Sea Biodiversity Database (from www.caspianenvironment.org) has it at 400-600 m in the southern Caspian in cold winters but later states it keeps at 15-32 m. Winter temperatures at which this species is found are 6-7C. Depths are 25-32 m in winter, more shallow in summer but below 9 m. Knipovich (1921) reports this species in a depth range of 52-77 m in Iranian waters. It tolerates a range of 3-25C and spawns at salinities of 0.7-11.0, although preferring 4.0-7.5. The Caspian Sea Biodiversity Database (from www.caspianenvironment.org) estimates a population of 1.1125 billion fish.

Age and growth

Life span is about 9 years and female lengths and weights exceed those of males throughout life. On average, males weigh less than half the weight of females since females carry a heavy egg load. Growth is most intensive in the first two years of life and slows thereafter (Chang, 1972). Males mature at age 2 and females at age 3.

Food

A rapacious fish which takes young herrings and kilka, Atherina and even Benthophilus (Lnnberg, 1900b) as well as large crustaceans such as mysids and gammarids. It is a cannibal. This shad overwinters and feeds in the south Caspian Sea (Chang, 1972).

Reproduction

The spring spawning migration (end of April to end of May) enters the north Caspian Sea and fish are mostly 15-25 cm in body length. Males mature at a younger age than females as evidenced by fish 3-4 years old predominating among females and fish 2-4 years old among males in the north Caspian catch. Spawning takes place in May (peaking in the first 10 days) and most fish are returning for the second time. Spawning temperatures are lower than in Alosa caspia, being only 13-14C although the peak is at 19-20C. Spawning occurs in il'mens, the sea where there is a freshwater discharge such as near the Volga River mouth, and in the northeastern sea. Females may spawn up to 6 times and males up to 5 times (Chang, 1972). Spawning takes place in shallow water at 1-6 m depths. Fecundity is up to 318,852 eggs. The young migrate southwards.

Parasites and predators

The Caspian seal, Pusa caspica, is a predator on this species (Krylov, 1984).

Economic importance

An important commercial species in the central and northern Caspian, taken on their way to, and on, the spawning grounds. The fishery in Azerbaijan during 1937 caught fish on average 17 cm long and 62 g in weight, most fish being 2-3 years old. The Caspian catch in the period 1936-1939 reached a peak of 8,800 t annually. Fish are caught with beach seines, stationary nets and drift nets.

Conservation

Stocks in Iranian waters are reputed to be depleted. Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include numbers unknown, range unknown, absent in other water bodies in Iran, absent outside the Caspian Sea basin.

Further work

The biology of this species in Iranian waters and the stocks or taxa found there need to be elucidated.

Sources

See under family heading.

Iranian material: CMNFI 1970-0531, 15, 49.9-108.7 mm standard length, Mazandaran, Larim River (3646'N, 5258'E); CMNFI 1970-0532, 1, 137.4 mm standard length, Gilan, Caspian Sea near Bandar-e Anzali (3728'N, 4927'E); CMNFI 1970-0543A, 2, 78.8-80.2 mm standard length, Gilan, Caspian Sea at Hasan Kiadeh (3724'N, 4958'E); CMNFI 1970-0581, 1, 102.1 mm standard length, Gilan, Caspian Sea near Hasan Kiadeh (3724'N, 4958'E); CMNFI 1979-0788, 3, 96.0-114.9 mm standard length, Mazandaran at Khadje Nafas (3700'N, 5407'E); CMNFI 1980-0136, 3, 107.3-127.6 mm standard length, Mazandaran, Fereydun Kenar River (3641'N, 5229'E); CMNFI 1980-0157, 2, 96.6-101.1 mm standard length, Mazandaran, Gorgan River estuary (3659'N, 5359'30"E); CMNFI 1980-0908, 1, 77.9 mm standard length, Gilan, Safid River estuary (ca. 3728'N, ca. 4954'E).

Comparative material: BM(NH) 1954.6.24:8-10, 3, 150.5-177.0 mm standard length, Caspian Sea (no other locality data).

Alosa sphaerocephala
(Berg, 1913)

Common names

shagmahi-ye Agrakhan.

[kruglogolovyi puzanok or roundheaded shad, Agrakhanskii puzanok or Agrakhan shad, both in Russian].

Systematics

The holotype of Clupeonella sphaerocephala from Agrakhan Bay, at Tyulenii Island, Turali in the northern part of the Caspian Sea is in the Zoological Institute, St. Petersburg under ZISP 15928 with more than 30 paratypes (Eschmeyer et al., 1996).

Key characters

Characterised by a relatively deep and compressed body likened to a "shad" shape, not as elongate and rounded as in some related species which are likened to a "herring" shape. The upper and lower head profiles are obviously rounded. The upper edge of the lower jaw is crescent-shaped. Total gill rakers 25-45, long (equal to or longer than the gill filaments), and thin. Teeth are well developed in both jaws.

Morphology

Dorsal fin with 3-4, usually 4, unbranched rays and 13-15 branched rays, anal fin with 3-4, usually 3, unbranched rays and 17-20 branched rays. Vertebrae 47-51.

Sexual dimorphism

None reported.

Colour

The back is dark with an olive tint, the tip of the snout is occasionally black and the pectoral fins are dark. There is a black spot behind the operculum and occasionally a row of such spots.

Size

Reaches 25 cm.

Distribution

Found in the Caspian Sea including Iranian waters.

Zoogeography

This species is endemic to the Caspian Sea.

Habitat

This species does not enter fresh waters. It is most common along the eastern shore of the northern part of the sea in spring where spawning occurs and along the northern shore of the northern part of the sea in summer. Knipovich (1921) reports this species from Iranian waters in a depth range of 52-77 m.

Age and growth

Unknown.

Food

Unknown, although presumably similar to other shads.

Reproduction

Spawning takes place in the northeastern Caspian from mid-May to the end of June peaking at 18-20C, most frequently in a salinity of 8-11 and in depths around 3-8 m. The young move south in late autumn, as late as November, the last clupeids to leave this area. Fecundity is about 20,000 eggs.

Parasites and predators

The Caspian seal, Pusa caspica, is a predator on this species (Krylov, 1984).

Economic importance

This species is caught only in small numbers.

Conservation

The status of this species is unknown.

Further work

This species is poorly known biologically and studies in Iranian waters should be carried out on its life history.

Sources

Iranian material: None available.

Comparative material: BM(NH) 1954.6.24:11-13, 3, 145.6-162.1 mm standard length, Caspian Sea (no other locality data).

Alosa volgensis
(Berg, 1913)

Recorded from Iranian waters by Kottelat and Freyhof (2007) but presence needs confirmation by specimens.

Genus Clupeonella
Kessler, 1877

This genus is found in the Black and Caspian seas basins with 5 species, 3 of which are in the Caspian Sea and in Iranian waters.

Clupeonella species are distinguished from sympatric Alosa species by smaller size, a small and toothless mouth, adipose eyelids are small or rudimentary, no spots on the flank, no elongate scales (ala) at the base of the caudal fin, no vomerine teeth, the lack of a notch at the mid-line of the upper jaw, and by the last two anal fin rays being elongated.

Species in this genus live entirely in the sea, or in fresh water, or migrate between the two. Eggs are pelagic and have a large oil globule.

The general Farsi name for these fishes is كيلكا (= kilka or kelka, i.e. "sprat", although sprat is erroneous according to Berg (1948-1949) who uses tyulka for these fishes).

The three Clupeonella species have been fished in modern Iran since December 1971 but the commercial catch did not exceed 15,000 tonnes. Earlier catches date back only to 1939 with an annual catch of about 100 t in 1943-1949 exported in a marinated form to the Soviet Union (Alam, no date). Curiously, the abundance of kilka has long been known as Kinneir (1813) records "and herrings are in such abundance, that after a storm, the shores of Ghilan and Mazanderaun are nearly covered with them". Caddy (1984) refers to the kilka fisheries of the Iranian Caspian by the scientific name Sprattus sprattus but this is an error.

Caddy (1984) indicated that there were problems in marketing and utilizing these fishes in Iran even though up to 50,000 t could be caught annually (200,000 t elsewhere in the same article). Their best use was probably as food for predators such as Sander lucioperca, Esox lucius and Salmo caspius. A study by Razavi Sayad (1993b) suggested a ceiling of 100,000 t was possible. The Caspian Sea resources of kilka is estimated at 800,000 t from which 340,000 t can be exploited (Abzeeyan, Tehran, 6(8):IV, 1995).

The catch reached 51,000 t in 1994 from none 10 years previously (Food and Agriculture Organization, Fisheries Department, 1996) and was 36,000 t in 1997-1998 (IRNA, 31 March 1998) and 85,000 t in 1998-1999 (Fazli and Roohi, 2002). The catch for the first 6 months of the Iranian year was 17,000 t, taken by 70 trawlers and a 10% increase over the previous year (IRNA, 20 October 1998). Fishermen in Gilan caught 50,000 t annually in the late 1990s (Tehran Times, 5 September 1999). A reported catch of 56,000 t was made in 1999-2000, a 13% increase over the previous year (IRNA, 27 March 2000). A later estimate expects the kilka catch to reach 66,000 t by the year 2000 (Abzeeyan, Tehran, 5(9):IV, 1995). Fazli (2006a) records that kilka fishing ships discharge their catches at three ports, Babolsar and Amirabad in Mazandaran and Anzali in Gilan. The catch decreased from 28,000 t to 19,600 t in Mazandaran and from 57,000 to 42,600 t in Gilan from 1999 to 2000. The catch per unit effort also decreased from 3900 kg to 2500 kg over the two years. Anchovy kilka dominated the catch but the frequency fell from 85-90% to 76% of the catch and common kilka sharply increased. Common kilka had been caught in spring and summer but in 2000 they were taken in all months. The average length of anchovy kilka declined from 96.3 mm in 1997 to 87.3 mm in 2000 and this was also reflected in the age structure, 5+ and 6+ fish being rare. The presence of the ctenophore, Mnemiopsis leidyi, was thought to be damaging stocks (Fazli and Roohi, 2002). Darvishi et al. (200$) studied dietary overlap between the ctenophore and the anchovy kilka (see below). Fazli (no date) studied kilka catches off Mazandaran in 1996-2000. Fishing occurred at night and lasted 7.78-8.22 hours. The maximum catch at 42.8% was taken in October, November and December with a minimum catch in June. The least annual catch per vessel occurred in 1999-2000 (499,401 kg).

A study utilizing an echo-sounder and a pelagic trawler concludes that the maximum biomasses for the three Clupeonella species in the southern Caspian Sea are in winter (422,300 t) and autumn (326,900 t) while in summer and spring values are lower at 275,100 t and 260,800 t respectively. The population consists of 66.1% anchovy kilka (C. engrauliformis), 18.9% bigeye kilka (C. grimmi) and 15% common kilka (C. caspia) (Iranian Fisheries Research and Training Organization Newsletter, 14:6, 1996). Note that later, the Iranian Fisheries Research and Training Organization Newsletter (17:3, 1997) gives kilka biomass in the southern Caspian Sea as winter 22,300 t, autumn 26,900 t, summer 75,100 and spring 60,800 t, presumably lacking the initial digit, and the percentages of kilka species in the biomass are also wrong. This is corrected in a subsequent newsletter (Iranian Fisheries Research and Training Organization Newsletter, Tehran (18:43, 1997) but the corrected percentage biomasses are given as 66% for C. engrauliformis, 19% for C. caspia (as C. delicatula) and 15% for C. grimmi. It is unclear whether grimmi or caspia is the second most important kilka species. Pourgholam et al. (1996) give a stock assessment for kilkas in 1995-1995 using the hydro-acoustic method.

C. engrauliformis dominates the catch in Iran at 91.8%, followed by C. grimmi at 6.84% and by C. caspia at only 1.35%. The 2+ and 3+ year classes account for 69.95% of C. engrauliformis, 81.06% of C. grimmi and 80.88% of C. caspia catches. Catch rates of kilka on the top ranking 17 fishing grounds of 56 studied range from 800 to 1200 kg per unit effort per hour while traditional grounds have rates of 400-800 kg per unit effort per hour. The kilka are caught by attraction to lights and netting or pumping the catch into specially constructed ships. The kilka fishing fleet of Iran expanded in the 1980s and 1990s. There were 30 active vessels in Mazandaran in 1994, each with a capacity up to 30 tons (sic, probably tonnes here and elsewhere for modern catches) (Abzeeyan, Tehran, 4(10):IV, 1994). The Mazandaran Kilka Cooperative Companies Union had 75 boats in 2000 (Tehran Times, 31 December 2000). Gilan planned to construct 12 fish meal factories each with an annual capacity of 1000 t and 10 kilka canneries also with 1000 ton capacities (Abzeeyan, Tehran, 4(4):III, 1993). Catches off Gilan alone from April 1994 to January 1995 increased 59% compared to the same period in 1993-1994, exceeding 20,000 t (Abzeeyan, Tehran, 6(1):II, 1995). The catch off Mazandaran from March 1994 to March 1995 was 15,400 t, an increase of 10% over the previous year. About 1000 t were processed for human consumption and the rest for fishmeal production (Abzeeyan, Tehran, 6(2):V, 1995). The total kilka catch for Iran has increased to 45,000 t annually and efforts were being made to increase it to 110,000 t (Abzeeyan, Tehran 4(5):IV, 1993). The catch in 1995 was 32,000 t with 64.7% from Mazandaran and 35.3% from Gilan, with the maximum catch occurring in April (Abzeeyan, Tehran, 7(6):II, 1996). Catches declined from 95,000 t in 1999 to 15,497 t in 2003 (Sayyad Bourani et al., 2008). Annual Soviet catches reached 37,000 t in 1956 but this declined to 300-1500 t by the end of the 1970s or 0.2-0.8% of all kinds of tyulka or kilka in the Caspian Sea. Turkmenistan harvested 7660 and 8500 t in 1995 and 1996 although previously almost 45,000 t valued at $22.5 million had been taken before equipment deteriorated (http://bisnis.doc.gov/bisnis/isa/9805fish.htm, downloaded 14 March 2000). Stocks remain large even though kilka are heavily fished.

Kilka are smoked, salted, canned in sauce and oil and marinated according to a traditional recipe and seasoned with fruits, herbs and vegetables (Keivany and Nasrollahzadeh, 1990; www.netiran.com/business.html, downloaded 31 October 2003). Moini and Koochekain (2003) give details of fish sauce production from kilkas using traditional, microbial and enzymatic methods, along with taste tests. Vacuum packaging of fresh, smoked and salted kilka has been investigated in Iran (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 45-46, 1997) and studies on processing kilkas as fish balls have also been carried out (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 40, 1996). Koochekian Sabour and Moini (2009) describe investigations on using Iranian kilkas to produce a fermented fish sauce for marketing in Southeast Asian countries. One company markets kilka in a clear package which gives the product a bright and colourful appearance. Kilka have even been made into crackers (Iranian Fisheries Research and Training Organization Newsletter, Tehran, 18:6, 1997; Shojaei, 1998). Kilka have also been made into oil as a by-product of the fish meal industry (Iranian Fisheries Research and Training Organization Newsletter, 27:3, 2001). Omega-3 fatty acids have been extracted from kilka oil under laboratory conditions (Salmani Joloudar et al., 2009). M. Shivazad , H. John Mohammady, A. A. Yousef Hakimi and H. Fazaely (http://iman.ut.ac.ir/news/agr.htm, downloaded 12 December 2004) discuss the use of Clupeonella engauliformis as fish meal in animal nutrition and analyse the protein quality and Faeed et al. (2006) studied spoilage in kilka meal from bacteria and fungi. The Iranian Fisheries Research and Training Organization Newsletter (20:4, 1998) and Rezaei et al. (2003) report on methods of transporting kilka in cold water and crushed ice to processing factories which were better than traditional methods. Salmani et al. (2001) recommend chilled sea water for preservation for human consumption. Motamedzadegan et al. (2009) found that partial hydrolysis of fish myofibrillar proteins using papain improves its functionality. Motalebi et al. (2010) investigated the use of whey protein coating on quality and shelf life of kilkas; it can enhance quality and increase frozen shelf life in fish stored for up to 4 months. Khanedan et al. (2011) found that an edible film of sodium alginate on dressed kilka increased shelf life. Valipour Meri et al. (2011) showed that Bacilus licheniformis can decrease significantly the aflotoxins in kilka fishmeal. Khoshkhoo et al. (2012) examined protein and lipid changes in fish protein concentrate made from kilkas over six months showing greater changes in Modified Atmosphere Packaging compared to Vacuum Packing and less changes at lower storage temperatures.

The kilka fisheries are threatened by the comb jelly, Mnemiopsis leidyi, which arrived in the Caspian in 1995 in the ballast water of ships and spread through the entire sea by the year 2000, feeding voraciously on zooplankton. It is now known as the "Caspian monster" despite its small size of 5 cm (Muir, 2001). It doubles in size in one day, reaches maturity in two weeks and then produces 8000 young each day (Muir, 2001). The fisheries collapsed by 50% in a few months, catches by one fisherman falling from being 3-6 t a night to half a tonne. Ghadirneja (2003) reports that C. engrauliformis originally dominated the kilka catch at 85-90% but has dropped to 55% through the impact of the comb jelly which has up to 2285 individuals per cubic metre in the southwest Caspian Sea.  Fazli et al. (2009) describe a multi-species approach for stock management, allowing for the decline of C. engrauliformis and increase in C. caspia in Iranian waters through competition with the ctenophore. The fisheries may recover somewhat after the comb jelly population collapses (Tidwell, 2001b) or if a predator, Beroe ovata, is introduced and can survive in the less saline waters of the Caspian Sea (Muir, 2001). Studies indicate it can survive the brackish Caspian Sea water, feed on the comb jelly and not feed on other plankton (Iranian Fisheries Research Organization Newsletter, 36:35, 2003). The following catch records for the total kilka catch in Mazandaran in tonnes is courtesy of F. Darvishi (pers. comm., 2003) and shows the drastic decline caused by the ctenophore, as well as monthly variations in catches:-


Months/Years 1998 (1377) 1999 (1378) 2000 (1379) 2001 (1380) 2002 (1381) Mean
March-April (Farvardin) 2848 2703 4644 1217 876 2458
April-May (Ordibehesht) 1116 607 972 1422 195 862
May-June (Khordad) 370 763 1819 125 158 647
June-July (Tir) 1392 919 194 425 444 675
July-August (Mordad) 2152 2306 433 614 249 1151
August-September (Shahrivar) 3117 2010 581 528 336 1314
September-October (Mehr) 3103 6184 1785 432 575 2416
October-November (Aban) 4120 3468 2305 3051 1196 2828
November-December (Azar) 3835 3410 2655 993 - 2723*
(2179)
December-January (Dey) 2754 1735 620 1082 - 1548*
(1238)
January-February (Bahman) 3968 1262 2146 1586 - 2241*
(1792)
February-March (Esfand) 2815 1667 1192 1903 - 1894*
(1515)
Total 31,590 28,034 19,648 13,378 4029  

* = averaged over 4 and (5) years.

The species composition of kilkas changed after the introduction of the comb jelly comparing the year 2000 and before with the year 2002 - the common kilka changed from about 1-5% to about 30%, the bigeye from about 10-15% to 0/2% and the anchovy kilka from about 85-90% to about 70% (Iranian Fisheries Research Organization Newsletter, 36:2, 2003). The catch per unit effort (catch per vessel per fishing night) fell from 4 t to 1 t. The catch during 1997-1999 of anchovy kilka fell from 51,300 t to 491 t and bigeye kilka from 7600 t to 309 t while common kilka rose from 1500 t to 24,600 t (Iranian Fisheries Research Organization Newsletter, 65:4, 2011). Parafkandeh Haghighi and Kaymaram (2012) found, for the years 2006-2007, that the common kilka was the dominant species (89.7%) while the anchovy kilka was at only 8.7% after previously being the dominant species. This was attributed to the comb jelly which occupied the anchovy kilka habitat at depths greater than 50 m. The total catch of kilkas fell from 95,000 t in 1999 to less than 20,000 t in 2007. The fishery moved to areas with depths less than 50 m, the main reason for the change in species composition.

In 2004, more than 200 fishing boats had been forced to stop operations. The kilka stock has been reduced from 400,000 t to 80,000 t over the past 4 years and the catch fell by 34,000 t (www.iranmania.com, downloaded 4 October 2004). See also the section on the Caspian Sea basin in the Introduction. Mamedov (2006) gives details of the biology and decline of kilkas in Azerbaijan waters.

The Caspian seal was once a major predator on kilkas but the number of seals has declined on the Kazakhstan and Iranian coasts from 300,000 to 5000 in recent years through DDT pollution, viral infections and food shortages (Hashemi, 2001).

An account on the biology and identification of Caspian kilka in Farsi is given by Emadi (1991) and Fazli (1990), Fazli and Besharat (1998) and Poorgholam et al. (1996) give accounts of biology and catches in Iran in Farsi.

Clupeonella caspia
Svetovidov, 1941

Common names

rizeh keraye (= tiny ?), rizeh kuli, kilka-ye ma'muli or kilka-e-maamooli (= common shad).

[xazar kilkasi in Azerbaijanian; adaty kulke balyk in Turkmenian; Kaspiiskaya tyul'ka or kil'ka (i.e. Caspian tyulka or kilka), tyulka, obyknovennaya tyul'ka (i.e. common tyulka), all in Russian; common kilka, common Caspian kilka, sardelle, Caspian sprat, Black Sea sprat].

Systematics

Formerly identified as Clupea cultriventris, originally described from the northern shore of the Black Sea. Clupea delicatula Nordmann, 1840, described from Odessa market on the Black Sea, is a synonym of C. cultriventris and a lectotype is in the Zoological Museum. St. Petersburg under ZISP 2254 with paralectotypes also under ZISP 2254, as designated by Svetovidov (1952). Clupeonella delicatula caspia Svetovidov, 1941 was considered to be a synonym and was described as from the "Caspian Sea, where it is met with almost everywhere, from very saline parts (Kaydak Bay) to quite fresh. Enters the mouths of the Volga and the Ural rivers, ascending sometimes very far upstream". The holotype is from the Volga Delta and is under ZISP 15883 (Svetovidov, 1952). Kottelat and Freyhof (2007) consider this subspecies to be a a distinct species found in the Caspian Sea with cultriventris restricted to the Black Sea. Reshetnikov et al. (1997) consider recognition of this subspecies as questionable.

The Caspian Sea taxon, Clupeonella caspia, has a lectotype, 152 mm long, designated by Svetovidov (1952) in the Zoological Institute, St. Petersburg (ZISP 15883).

Clupea cultriventris is spelled cultiventris in some parts of Eschmeyer et al. (1996), apparently in error. Three syntypes of Clupea cultriventris may be in the Musum National d'Histoire Naturelle, Paris under MNHN 3681 (Svetovidov, 1952; Eschmeyer et al., 1996).

Clupea cultriventris var. tscharchalensis Borodin, 1896 from Lake Charkhal in the Ural River basin is variously listed as a variety, morpha or a distinct species (see Svetovidov (1952) and Kottelat and Freyhof (2007)).

mtDNA studies of fish from Mazandaran and from Gilan showed statistically significant differences in haplotype frequencies, indicating genetically different populations (Laloei et al., 2006).

Key characters

This species has a moderately deep body (21-27% of standard length), a short and wide head (interorbital width 17.5% or more of head length), a sharply keeled belly, and pointed pectoral fin tips.

The Caspian subspecies is distinguished from the type subspecies of the Black Sea by having shorter pectoral (15.5-19.0% of standard length) and pelvic fins (8.5-12.5% of standard length), although ranges overlap, a shallower body, and a shallower and shorter head. It also grows faster and is more fatty than the Black Sea subspecies.

Morphology

The dorsal fin has 3-4 unbranched rays, usually 3, followed by 11-14 branched rays and the anal fin has 1-3 unbranched rays, usually 3, and 14-19 branched rays. Scales in lateral series 42-55. There are 24-30 belly scutes and 41-62 (rarely to 64), usually 51 or more, gill rakers. Vertebrae 40-44 (rarely to 45) compared to 44-47 in the anchovy kilka and 46-48 in the bigeye kilka, probably as a result of higher water temperatures during development compared to other kilka species (Prikhod'ko, 1979b).

Sexual dimorphism

Sexual dimorphism is only evident during egg development when the belly of females is swollen.

Colour

The back is blue-green or light-green, the flanks silvery and the belly silvery-white or golden-yellow. Fins are hyaline except the dorsal fin which has a central dark but faint stripe and the caudal fin which is darkish at the base. The iris is black.

Size

Reaches 14.5 cm standard length and 19 g.

Distribution

Found in the Black and Caspian seas, tributary rivers and some adjacent lakes. In Iran, it is reported from sea and also the confluence of the Pasikhan and Pir Bazar rivers of the Anzali Mordab, the Anzali Mordab and its outlets by Holčk and Olh (1992) and from the Safid River and Anzali Talab (= Mordab) by Abbasi et al. (1999). Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea in Iranian waters.

Zoogeography

This species is part of a marine fauna encompassing the Black and Caspian seas, surviving in the reduced salinity of the latter.

Habitat

The habitat of this species in the Caspian Sea is the coastal zone of the sea at depths less than 100 m, more usually less than 50-70 m, over a wide range of temperatures (2.6-27.6C for adults, higher for larvae, and possibly lower temperatures since they are found under ice and probably over 28C according to some reports), and in fresh and hypersaline waters (to 36). The young can develop in water at 16. Southern populations live in a more saline habitat than northern and central Caspian populations which are mostly in fresh water. This tyulka may not migrate far but does move between summer-winter feeding and spring-early summer spawning grounds. Large schools are found 0.5-2.0 km from shore at depths of 20-25 m on the eastern coast of the Caspian Sea, descending deeper if water temperatures rise and coming up to about 8 m in autumn as temperatures fall. In winter this species is found at about 30-40 m deep where the temperature range is 7-10C, warmer than surface waters. Larvae and young remain in shallow coastal areas. Knipovich (1921) reports a fish from a depth range of 235-300 m in Iranian waters but populations at these depths are small (Iranian Fisheries Research and Training Organization Newsletter, 14:6, 1996). The Caspian Sea Biodiversity Database (from www.caspianenvironment.org) states that the largest concentrations are found at 3-7 with most intensive spawning at 2-4.

It is the most widely distributed kilka and with the other kilka species the most abundant fish in the Caspian Sea (Prikhod'ko, 1979b). Large schools can be found by day but these disperse at night. It overwinters in the southern Caspian Sea and some individuals move north to spawn and feed in April. The Caspian Sea Biodiversity Database (from www.caspianenvironment.org) estimates the population to number 224 billion fish, with 96 billion fish in the south Caspian. The south and north Caspian Sea stocks are about equal in number after a decline in copepod biomass in the north. The relative frequency of this species compared to other kilkas increased after the invasion of Mnemiopsis leidyi, by more than 10% (Fazli, 2006b; Fazli et al., 2006).

Age and growth

Osipov and Kiyashko (2008) found that using otoliths gave more reliable estimates than using scales for ageing. The Caspian subspecies grows faster than the Black Sea subspecies. Together with the sturgeons, this species comprises 82.1% of the fish biomass in the Caspian Sea. Condition in this species is better in winter because of the summer-autumn feeding period after spring spawning compared to C. engrauliformis in the Big Kizil-Agach (= Bol'shoy Kyzylagach or Imeni Kirova) Bay of Azerbaijan (Badalov, 1972). Local populations have differing growth regimes depending on the productivity of these areas (Prikhod'ko, 1979b) and there are great variations on a yearly basis too. Southern populations grow faster than northern ones in their first year. Females grow somewhat faster than males (9.0 g versus 7.3 g average weight along the Dagestan coast for example), and life span is about 6 years. This species is mature there at 1 year and average life span is about 3 years.

Females dominate the population in Iran and sexual maturity is attained usually at age 2 and 2-4 year olds dominate catches but life span is up to 8 years (Iranian Fisheries Research and Training Organization Newsletter, 14:6, 1996; Abtahi et al., 2002). Fazli (2006b) found age classes 0+ to 5+ in Iranian waters with 0+ to 3+ making up 95% of the fish in 1997-1999. In 2000, age classes 0+ and 1+ were reduced in numbers and 2+ to 4+ fish comprised 93.8%. Abtahi et al. (2004) examined fish from the conical net and light catch at Babolsar and found average fork lengths were 69.82 mm, 83.56 mm, 88.38 mm and 88.43 mm while weights were 2.2 g, 4.18 g, 4.77 g and 5.06 g for fishes at maturity stages I, II, II and IV. Fazli et al. (2007) studied this species from 1995 to 2004 in Iranian waters, sampled at landing sites at Amirabad and Babolsar in Mazandaran and Anzali in Gilan. Growth parameters were L = 132 mm, K = 0.259/yr. t0 = -1.285/yr. The instantaneous coefficient of natural mortality was 0.506/yr, the instantaneous coefficient of total mortality (Z) was 1.62/yr and the instantaneous coefficient of fishing mortality varied over 10 years from 0.125/yr to 1.487/yr. Annual survival rate (S) was 0.200/yr. Age at first capture was 2.8 years. The von Bertalanffy growth equation was Lt = 132 (1-e-0.259(t +1.285)). Ages ranged from 1 to 7 years with age groups 2, 3 and 4 dominating at different periods. Mean fork lengths were 59.3, 77.5, 87.4, 97.2, 104.5, 111.9 and 116.8 mm. Females dominated in each month except April, averaging 0.47:1, possibly due to differing attraction to lights used in the fishery. Biomass increased from 16,000 mt in 1995 to more than 41,000 mt in 2002, declining to less than 28,000 mt in 2004. The increase was simultaneous with a sharp decline in anchovy kilka, changes in zooplankton composition and abundance, and especially an increase in zooplankton species favoured by this kilka. Currently this kilka is overfished. Karimzadeh et al. (2010) and Karimzadeh (2011) examined fish from the Babolsar region off Mazandaran and calculated growth parameters as L = 143.5 mm, K = 0.30/yr-1 and t0 = -1.02/yr, instantaneous coefficient of natural mortality was 0.671 yr-1, fishing mortality was 0.849 yr-1, and the current exploitation rate was estimated as 0.55 and this species is now overfished. Aliasghari et al. (2012) examined Iranian fish in 2010 and found a length-weight relationship of W = 0.000001FL2.92, L = 128.7 mm, K = 0.41/year, t0 = -0.59/year,  survival rate = 0.239/year, natural mortality = 0.448/year, fishing mortality 0.983/year, exploitation rate 0.687 (indicating overfishing), age groups 1-6 years, average age 3.27 years, 3-year-old fish were the largest age group (45.24% of the catch), and males were dominant (1:0.779). Mean length and weight of the population increased but mean age decreased in recent years.

Food

Plankton is the main food and copepods predominate but diet also includes Cladocera, Balanus larvae and clam larvae. The dominant food item is the copepod Eurytemora grimmi, particularly in winter when plankton biomass is lowered in the Bol'shoy Kyzylagach Bay of Azerbaijan. The food of the common kilka is more varied than the other kilka species simply because of its habitat in shallow coastal areas (Badalov, 1972; Prikhod'ko, 1979b). Older fish take larger and faster crustaceans and consume less food in proportion to body size as they grow. The most intensive feeding is in summer and autumn, decreasing in winter and during reproduction. Food is taken during the day. Roushan Tabari et al. (2009) examined fish from a fishing vessel of Mazandaran and found highest feeding activity in April with 280153 prey items per fish weighing 2.91.6 mg. Balanus nauplii and cypris larvae comprised 93% and Acartia 7% at this time with increasing spring temperatures and reproduction, but the copepod Acartia biomass dominated from October to February.

Reproduction

Spawning occurs in January-February in the southern Caspian, later in the north, mainly in depths less than 10 m and where salinity is low to average for the Caspian Sea (Badalov, 1972; Prikhod'ko, 1979b). The largest southern Caspian population spawns near the mouths of the Volga and Ural rivers (Kozlovsky in Hoestlandt, 1991). Spawning is most intensive at 11C, but occurs at 10-20C. Spawning is intermittent and lasts from mid-April to July. Peak spawning in Iranian waters of Mazandaran Province is April-May with an average fecundity of 28,240 eggs (Abtahi et al., 2002). Fazli (2006b) recorded mass spawning in Iranian waters in April, continuing on until August. Eggs are released in water 0.5-9.0 m deep at a salinity range of 0.02-15, perhaps as high as 29.15. Fecundity reaches 60,000 eggs and egg diameter 1 mm, 0.48-1.46 mm for fertilised eggs. Relative fertility is 4-13 times greater than in Alosa species. Holčk and Olh (1992) consider that it may spawn in rivers entering the Anzali Mordab. The studies of Fazli et al. (2006; 2007) showed that reproduction started in March, peaked in May and finished at the end of August. Half the females were mature at 84.3 mm fork length. Aliasghari et al. (2012) found from gonadosomatic indices and sexual maturity stages that spawning in Iran began in February and peaked in May and June.

Parasites and predators

Samples of this species from Babol Sar and Bandar Anzali contain the digenean parasites Pseudopentagramma symmetrica (probably Pronoprymna ventricosa after Youssefi et al. (2010)) and Bunocotyle cingulata, the acanthocephalan Corynosoma strumosum, metacercariae of a Bucephalus species, and larvae of a Contracaecum and an Anisakis species (Iranian Fisheries Research and Training Organization Newsletter, 11:4-5, 1996; Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 28, 1997; Shamsi and Dalimi, 1996; Shamsi et al., 1998). Ghayoumi et al. (2009) found that fish from Babol Sar harbour contained the intestinal helminths Corynosoma strumosum, Pronoprymna ventricosa, Contracaecum sp. larvae and Raphidascaris sp. larvae, diet being the main factor affecting diversity of the parasites. Varshoie et al. (2010) record the helminths Pseudopentagramma symmetrica (see above), Bunocotyle cingulata and Mazocreas alosae in this species from Iranian waters.

Clupeonella species are an important food fish for sturgeons (59.4% by weight of Acipenser stellatus diet in the Middle Caspian), Sander, herrings (Clupeidae) and the Caspian seal (Badalov, 1972; Krylov, 1984) as well as Salmo  caspius and Stenodus leucichthys (Kosarev and Yablonskaya, 1994).

Economic importance

It is caught by attraction to underwater electrical lights (Prikhod'ko, 1979b). The other subspecies is also of major importance in the Sea of Azov. The Caspian subspecies is caught in school seines in spring and purse seines in summer. In Iranian waters this species formed only a small proportion (1.35%) of the total kilka catch in a study by Razavi Sayad (1993b) and Fazli (2006b) gives values of 1.34%, 2.5% and 5.5% for the years 1990-91, 1997-98 and 1998-99 respectively. However, as the anchovy kilka catch declined, this species increased from 13.7% of the total catch in 1999 to 48.9% in 2003 (Sayyad Bourani et al., 2008). Naseri et al. (2010) studied lipid changes in canned kilka after long-term storage. Motalebi and Seyfazadeh (2011) used an edible whey protein coating on frozen common kilka and this helped retain a good quality in the product.

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food and as bait.

Conservation

Stocks on the Iranian coast are said to have been depleted but its ecological specialisation on zooplankton means there is comparatively little competition with other fishes. It is probably not in any immediate danger. Kiabi et al. (1999) consider this species to be of least concern in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, abundant in numbers, widespread range (75% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin.

Further work

The biology of this species in Iranian waters needs to be elucidated.

Sources

Counts are based in part on Svetovidov (1945a). See also under family heading.

Iranian material: CMNFI 1970-0531, 14, 78.0-88.6 mm standard length, Mazandaran, Larim River (3646'N, 5258'E); CMNFI 1980-0146, 7, 79.9-96.2 mm standard length, Mazandaran, Gorgan Bay at Ashuradeh-ye Kuchak (3650'N, 5356'E); CMNFI 1993-0146, 3, 80.2-98.2 mm standard length, Mazandaran, Gorgan Bay (no other locality data); CMNFI 1993-0167, 1, 96.6 mm standard length, Mazandaran, Caspian Sea, 10 km offshore (ca. 3649'N, ca. 5239'E); CMNFI 1993-0168, 3, 84.9-88.0 mm standard length, Mazandaran, Caspian Sea, 10 km offshore (ca. 3649'N, ca. 5239'E).

Clupeonella engrauliformis
(Borodin, 1904)

Common names

rizeh keraye (= tiny ?), kilka-ye anchovy or kilka-e-anchovi.

[ancousabanzar kilka in Azerbaijanian; ancous sekilli kulke balyk in Turkmenian; anchousovidnaya tyul'ka or anchovy-like tyulka, sardelle or sardel'ka, "sardinka" but incorrectly, all in Russian; anchovy kilka, anchovy sprat].

Systematics

No major synonyms. Originally described from Buinak, central part of the Caspian Sea. The lectotype is in the Zoological Institute, St. Petersburg (ZISP 13860) with paralectotypes as established by Svetovidov (1952) (Eschmeyer et al., 1996). Eschmeyer et al. (1996) give the date as 1906 but Reshetnikov et al. (1997) give 1904.

Key characters

This species has a slender body (16-19% of standard length), a short and wide head (interorbital width 16-18.5% of head length), a rounded belly, and pointed pectoral fin tips.

Morphology

Dorsal fin with 3 unbranched and 12-14 branched rays, anal fin with 3 unbranched and 15-19 branched rays. Scales in lateral series 45-49. Vertebrae 44-47, rarely to 48 compared to 41-44 in the common kilka (C. caspia). Gill rakers number 56-67. Belly scutes 23-31.

Sexual dimorphism

None reported.

Colour

The back and head are dark blue with violet, green or olive tints. These colours become brighter or turn black in dead fish. The fins are hyaline except the caudal fin which has a black base and the dorsal fin which has a central dark stripe.

Size

Attains 15.5 cm standard length.

Distribution

Found in the central and southern Caspian Sea, and in Iranian waters the southeast Caspian Sea, southwest Caspian Sea and the south-central Caspian Sea (Kiabi et al., 1999) as well as the Anzali Mordab, Babol Sar Beach and Gorgan Bay (Armantrout, 1980). Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea, the Anzali Talab and Gorgan Bay in Iranian waters.

Zoogeography

This species is endemic to the Caspian Sea.

Habitat

The anchovy kilka, along with other kilkas, is the most abundant fish in the Caspian Sea forming large concentrations in the central and southern Caspian wherever water depth exceeds 30 m. The anchovy kilka is estimated to be the most numerous kilka at about 77% (Ivanov and Katunin, 2001; Daskalov and Mamedov, 2007). It is generally found in the upper water layers but may descend to 120 m. Nearshore areas, inlets and water of a salinity below 8 are avoided. They can tolerate a salinity range of 8-14 but the main part of the population is found at 10-12 (Fazli et al., 2007). Overwintering takes place in the southern Caspian and the southern part of the central Caspian Sea at 8.5-9.0C and up to 13.5C. Schools extend their range into the central and northern Caspian in spring to feed (Prikhod'ko, 1979b). This species has a hibernation period in the south Caspian Sea, a spring migration of part of the population to the central Caspian, a feeding period in the central and south Caspian and an autumn prespawning migration to the south Caspian (Sedov and Rychagova, 1983).

In Iran larvae are found mostly in surface layers at 5-20 m while adults are found in deeper zones. males dominate in winter while females dominate in other seasons. The maximum juvenile density (fish <75 mm), comprising 36% of the population, is seen in the summer (Iranian Fisheries Research and Training Organization Newsletter, 20:7, 1998). Jolodar and Abdoli (2004) state it is most abundant at 100-150 m.

Age and growth

Abundance of young anchovy kilka, and hence future year-class strengths, depends on water temperature in autumn (October-November). Falling water temperatures, in the eastern Caspian for example, are caused by upwelling which brings nutrients to surface waters and promotes growth of plankton on which the kilka larvae feed (Prikhod'ko, 1979a). Females are somewhat larger than males in the spawning areas. Sexual maturity is attained usually at age 2 and 2-4 year olds dominate catches but life span is up to 8 years (Iranian Fisheries Research and Training Organization Newsletter, 14:6, 1996). This species shows the fastest rate of growth in the genus. Of the 8 age classes, 0+, 1+, 2+ and 3+ form 99.91% of the whole population (Iranian Fisheries Research and Training Organization Newsletter, 20:7, 1998). The same study showed that 18.6% of the population matures in the first year of life while 81% matures in the second. The mean age in coastal areas is 2.9 years, slightly higher than that in deep zones below 200 m where 0+ fish are more abundant. The Caspian Sea Biodiversity Database (from www.caspianenvironment.org) gives a population of up to 293 billion fish in the Caspian Sea.

Fazli et al. (2007) and Sayyad Bourani et al. (2008) studied these kilkas from catches with conical liftnets carrying underwater lights in the fisheries of Gilan and Mazandaran in the 1995-2004 period. Fish were aged using the sagittal otoliths. Length and weight ranges were 40-140 mm and 0.4-18.4 g with averages of 94.0 mm and 5.7 g (89.2-100.4 mm from 1999 to 2003 in Sayyad Bourani et al., 2008). The age range was 1-7 years (rarely to 8+ years in Parafkandeh Haghighi and Kaymaram (2012)). The dominant age group varied from age 2 to age 4, making up 40.6% to 57.7% of the catch (Fazli et al., 2007) or 5+ years with 4+-5+ making up 84.6% for 1999-2003 (Sayyad Bourani et al., 2008). Growth was high for the first year of life and then gradually decreased. The von Bertalanffy growth equation was Lt = 148(1-e-0.238(t+1.340)) (Fazli et al., 2007, and following data). The sex ratio varied with season and was significantly different from equal at male:female = 0.78:1 for adults. Females were more abundant from January to June and males predominated from September to November. Condition factors differed significantly between years, increasing from 1995 to 1996, being lowest in 1998 and then increasing to 2004, and between months, being lowest in January and February and then increasing in March. 50% of fish were mature at 84.5 mm fork length. Annual survival rate was estimated at 0.32, the instantaneous coefficient of total mortality (Z) was 1.14/year, natural mortality was 0.473/year. Age at first capture was estimated as 2.92 years. The total biomass declined from 186,000 t in 1996 to less than 12,000 t in 2004 and the exploitation rate for 1995-2004 varied between 0.340 and 0.815. Sayyad Bourani et al. (2008) give a K value of 0.598/year and a L of 110.13 mm. Natural, fishing and total mortality coefficients were 0.69, 0.31 and 1 per year respectively and the sex ratio was female:male = 68.2-31.8. These latter results for the 1999-2003 period show how value scan change when subsets of data are used. Fatemi et al. (2009) examined fish taken from commercial vessels in 2007 using lift nets and lights. Age structure ranged from 2 to 7 years and was dominated by the third year class (38.6%). Back-calculation methods were validated using otoliths to determine lengths. Karimzadeh et al. (2010) examined fish from the Babolsar region off Mazandaran and calculated growth parameters as L = 151.9 mm, K = 0.28/yr-1 and t0 = -1.12/yr, instantaneous coefficient of natural mortality was 0.633/yr-1 and the current exploitation rate was estimated as 0.41. Janbaz et al. (2012) give values for Iran from 2005 to 2007 of K = 0.375/year, L 131.7 mm, instantaneous coefficient of natural mortality was 0.49/year, fishing mortality was 0.51/year and total mortality 1.0/year, and exploitation rate was 0.51. Abundance declined over the three years from 18.8% to 8.5% and to 6%, catch per unit effort declined from 0.3 to 0.1 t, and the condition factor declined. Overfishing and the competitive ctenophore were the main causes of the decline.

Food

Plankton is the main food and copepods predominate but diet also includes Cladocera, Balanus larvae and clam larvae. The dominant food item is the copepod Eurytemora grimmi, particularly in winter when plankton biomass is lowered (Badalov, 1972). It can make up over 70% of its food. This copepod is more characteristic of the diet of this kilka compared to the other two species and the daily vertical migrations and seasonal movements of the copepod are mirrored by the kilka. The most abundant fish species in the Caspian depends on the most abundant member of the crustacean zooplankton (Prikhod'ko, 1979b). This species feeds in winter, unlike Clupeonella caspia. Bankehsaz (1996) surveys the fluctuation in fat content of this species through the year. Intensive feeding begins in spring as a preparation for spawning (Sedov and Rychagova, 1983). Spawning males show a positive response to light and so feed during the spawning season, while females do not. F. Darvishi (pers. comm., 2003) has demonstrated that the this species has a similar feeding niche as the exotic ctenophore Mnemiopsis leidyi and Esmaili Sari et al. (2002) determined that there is a similar diet in Iranian waters suggesting that a decline in stocks of the fish is the result of competition. Darvishi et al. (2004) studied catches of the anchovy kilka and the ctenophore in the southern Caspian Sea from August 2001 to October 2002. Dietary overlap was >89 in Babolsar samples and >84 in Nowshahr samples using the Schoener Index (presumably 0.89 and 0.84 where 0 is no dietary overlap and 1 is an identical diet). The ctenophore was also feeding on fish eggs but the effect of this was less than competition for food.

Reproduction

Spawning ends in late autumn and winter food requirements are higher than in spring-spawning C. caspia (Badalov, 1972). Areas for spawning in this species are extensive. Spawning is most intensive in July when temperatures are 13-24C and salinity 8-13 although the Caspian Sea Biodiversity Database (from www.caspianenvironment.org) gives peak spawning (70%) as in October-November. Fazli (2006a) gives spawning in Iran as spring and autumn but mass spawning takes place in in autumn. Spawning takes place in the central and southern Caspian along both eastern and western shores both in coastal regions and the open sea from late April to November. Mass spawning takes place at depths of 50-200 m and as a result eggs and larvae are carried over a wide area by the Caspian gyral current at these depths (Prikhod'ko, 1979b). Young hatch mainly in autumn and reach 4.5-8.0 cm at an age of 8-10 months (Prikhod'ko, 1979a). Eggs are up to 1.82 mm in diameter and fecundity reaches 39,900 eggs.

In Iran, 80% of the population spawn in autumn and the remainder in spring. Accordingly the fishery should be closed in October and November (Iranian Fisheries Research and Training Organization Newsletter, 19:5, 1998). The subsequent Iranian Fisheries Research and Training Organization Newsletter (20:7, 1998) states that 89% of the population spawns in autumn with September, at 68.3%, the major month. Fazli et al. (2007) found reproduction to start in June, peaking in October and then declining.

Parasites and predators

Samples of this species from Babol Sar and Bandar Anzali contain the digenean trematode parasites Pseudopentagramma symmetrica (probably Pronoprymna ventricosa after Youssefi et al. (2010)) and Bunocotyle cingulata, the acanthocephalan Corynosoma strumosum and larvae of the nematode Contracaecum sp. (Iranian Fisheries Research and Training Organization Newsletter, 11:4-5, 1996; Shamsi et al., 1996; Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 28, 1997; Shamsi and Dalimi, 1996; Shamsi et al., 1998). Clupeonella species are an important food fish for sturgeons (59.4% by weight of sevryuga diet in the Middle Caspian), Sander (Percidae) and herrings and the Caspian seal (Badalov, 1972; Krylov, 1984) as well as other fishes. Ghayoumi et al. (2009) found that fish from Babol Sar harbour contained the intestinal helminths Corynosoma strumosum, Pronoprymna ventricosa, Contracaecum sp. larvae and  Raphidascaris sp. larvae, diet being the main factor affecting diversity of the parasites. Varshoie et al. (2010) record the helminths Pseudopentagramma symmetrica (see above), Bunocotyle cingulata and Mazocreas alosae in this species from Iranian waters.

Economic importance

This species forms 80-90% of the catches of kilkas in former Soviet waters (Sedov and Rychagova, 1983) and, as noted above, 91.8% of catches in an Iranian study (Razavi Sayad, 1993b; Rezaei et al., 2003). High catches are related to the larger spawning and foraging range of this species compared to other kilkas and to its habitat in the Caspian gyre, an area of increased biological productivity (Prikhod'ko, 1979b). It is caught in former Soviet waters by attraction to underwater electrical lights attached to the middle of the mouth of a fine-mesh conical net or the sides of a fish pump (Ben-Yami, 1976). Fishing is suspended at full moons as the fish are dispersed (Saheli, 1999). Both large and small individuals are taken by these non-selective methods (Prikhod'ko, 1981). Incidental catches include Mugilidae (common), and Alosa spp., Atherinidae and the cyprinid Pelecus cultratus (all occasional) (Ben-Yami, 1976).

It is regarded as a valuable and cheap food resource in Iran where it is canned, made into sausages and surimi, and processed as fish meal (Shamsi et al., 1996; Moeini, 2002; Shabanpour et al., 2002,,2006). The catch per unit effort for funnel nets and midwater trawls is 2321 and 1014 respectively (Iranian Fisheries Research and Training Organization Newsletter, 20:7, 1998). Various studies on its preparation and storage as food have been carried out, e.g. Rezaei et al. (2002; 2003; Moeini et al., 2009).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food and as bait.

Conservation

Prikhod'ko (1981) recommends fishing in deeper waters where larger fish are concentrated to avoid an excessive take of young fish which favour the upper water layers. Stocks in the southern Caspian Sea are said to be depleted. Kiabi et al. (1999) consider this species to be of least concern in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, abundant in numbers, widespread range (75% of water bodies), absent in other water bodies in Iran, absent outside the Caspian Sea basin. Daskalov and Mamedov (2007) studied commercial catch data in the Caspian Sea generally and found a period of high catches from 1991 to 2000 with high spawning-stock biomass and relatively good recruitment. Catches peaked at 271,400 t, fishing mortality reached 1.8y-1 in 1999 and overfishing occurred. From 2001 to 2004, the stock collapsed, recruitment failed in 2001 and catches fell to 54,300 t in 2005. This was attributed to the spread of the ctenophore Mnemiopsis leidyi, with contributions from overfishing. Fazli et al. (2007) also concur that both overfishing and the invasive ctenophore caused the collapse of stocks. The catch in Iran declined from 71% of the total kilka catch in 1999 to 52.5% in 2003 (Sayyad Bourani et al., 2008). Janbaz et al. (2012) give figures for the collapse in Iran from 4250 t in 2005 to 924 t in 2007.

Further work

The biology of this species in Iranian waters needs to be elucidated.

Sources

Iranian material: CMNFI 1993-0167, 1, 99.5 mm standard length, Mazandaran, Caspian Sea (ca. 3649'N, ca. 5239'E); CMNFI 1993-0168, 4, 89.3-107.6 mm standard length, Mazandaran, Caspian Sea (ca. 3649'N, ca. 5239'E).

Clupeonella grimmi
Kessler, 1877

Common names

kilka-ye cheshmdorosht (= bigeye kilka).

[irikoz kilka in Azerbaijan; sardelle or sardel'ka, bol'sheglazaya tyul'ka or bigeye tyulka, bol'sheglazaya kil'ka or bigeye kilka, all in Russian; southern Caspian sprat].

Systematics

Clupeonella Grimmi was originally described from the central part of the Caspian Sea. The lectotype is in the Zoological Institute, St. Petersburg under ZISP 10934 as designated by Svetovidov (1952).

Harengula macrophthalma Knipovich, 1921 is a synonym. Four syntypes are in the Natural History Museum, London under BM(NH) 1897.7.5:41-44 (when examined were numbered 42-44, 3 fish, 29.9-33.5 mm standard length in poor condition, September 2007), with many others apparently in the Zoological Institute, St. Petersburg (Eschmeyer et al., 1996).

Key characters

This species has a moderately slender body (17-22% of standard length), a long and narrow head (interorbital width 13-15% of head length), a sharply keeled belly, and rounded pectoral fin tips.

Morphology

Dorsal fin unbranched rays 3-4, usually 3, branched rays 13-15, and anal fin unbranched rays 3, branched rays 14-21. There are 44-49, usually 46-48, vertebrae, more than in the other two kilka species and probably a consequence of the low water temperature larvae develop in. Belly with 26-32 scutes. Gill rakers 42-51.

The bigeye kilka is adapted to life in deeper water having, as its name indicates, big eyes with more rod cells and a weaker retina but also more transparent body tissues than other kilkas.

Sexual dimorphism

None reported except size.

Colour

The back and top of the head are dark.

Size

Reaches 14.5 cm standard length.

Distribution

Found in the Caspian Sea and concentrated in the south including Iranian waters. Abdoli and Naderi (2009) list it as from the southwest, southeast and south-central Caspian Sea in Iranian waters.

Zoogeography

This species is endemic to the Caspian Sea.

Habitat

The bigeye kilka is found further away from the coast than the anchovy kilka at depths over 50-70 m, down to 450 m, with large schools down to 130 m. It does not enter fresh water or low salinity areas, staying well away from the shore. There is a daily vertical migration, avoiding sunlight, and following food items. Larvae live in water temperatures of 5C. Overwintering occurs in the southern Caspian at temperatures of 9-11C, a migration to the central Caspian takes place in spring, with a return south in autumn (Prikhod'ko, 1979b).

Age and growth

Sexual maturity is attained usually at age 2, and 2-4 year olds dominate catches, but life span is up to 8 years (Iranian Fisheries Research and Training Organization Newsletter, 14:6, 1996). The female is larger than the male at the same age. Growth is slower than in C. engrauliformis. Males dominate the population (Iranian Fisheries Research and Training Organization Newsletter, 14:6, 1996; Fazli et al., 2005) but this study may have sampled spawning fish (see below).

Fazli et al. (2005) examined fish from the main landing ports (Babolsar, Amirabad and Anzali) found the mean fork length of fish increased from 95.87 mm in 1997 to 105.0 mm in 2000 but then decreased to 102.3 mm afterwards. Over this time period, fork length range became wider with specimens in the upper length classes representing most of the catch. Six age classes were present, 1+ to 6+ years. During 1998-1999, age classes 1+ to 3+ comprised more than 90% of the catch. In 2000, there was a decrease in age classes 1+ and 2+ and an increase in 3+ to 5+ classes. In 2001, age classes 3+ and 4+ decreased and classes 5+ and 6+ increased. The relative frequency of the bigeye kilka has decreased in recent years as a result of the introduction of the ctenophore, Mnemiopsis leidyi, a food competitor and predator on kilka eggs and young. Khorashadizadeh et al. (2006) found fish in the Babolsar area of the Iranian coast to have 5 age classes, dominated by the 4+ class. Fazli et al. (2009) examined changes in the population biology of this kilka over the period 1995 to 2001, attributed to the inavsive ctenophore. The overall sex ratio was 1.65:1 in favour of males, length-weight regressions were W = 0.00922L2.851 for females and W= 0.008021L2.907 for males, indicating a negative growth for both sexes, growth parameters were L = 142 mm, K = 0.28 year-1, and t0 = -1.39 years, the instantaneous coefficient of natural mortality was 0.460 year-1, and the instantaneous coefficient of fishing mortality varied between 0.469 and 0.980 year-1. Biomass increased from 36,900 mt in 1995 to more than 53,500 mt in 1998 but declined to less than 5900 mt in 2001. This was attributed to overfishing and the appearance of the ctenophore, a competitor for zooplankton food.

Karimzadeh et al. (2010) examined fish from the Babolsar region off Mazandaran and calculated growth parameters as L = 148.6 mm, K = 0.46/yr-1 and t0 = -0.18/yr, instantaneous coefficient of natural mortality was 0.881/yr-1 and the current exploitation rate was estimated as 0.26.

Food

Migratory mysids often predominate in the planktonic diet of this species. Fish fry are also eaten. Its foods are less diverse than that of other kilkas because the variety is less in the deeper waters this fish inhabits during the day. The three kilkas share the available habitat and its foods, the common kilka in shallow, coastal waters, the anchovy kilka in the upper layers of the open sea and the bigeye kilka in deeper water of the open sea (Badalov, 1972; Prikhod'ko, 1979b).

Reproduction

Spawning is extended, from January through to September but is most intense in spring and autumn (Prikhod'ko, 1979b). Males predominate in the spawning areas, remaining there while females leave immediately after spawning. Males are mainly at 10-20 m and females at 20-25 m during the spawning season. Water temperatures at 6-13C and salinity 12.6-13.0. Fecundity is 28,300 eggs. In Iranian waters, mature fish ready to spawn are always present in catches in winter and early spring (Fazli et al., 2005). Khorashadizadeh et al. (2006) found fish in the Babolsar area of the Iranian coast to have peak spawning in early January.

Parasites and predators

Samples of this species from Babol Sar and Bandar Anzali contain the digenean parasites Pseudopentagramma symmetrica (probably Pronoprymna ventricosa after Youssefi et al. (2010)), Bunocotyle cingulata, the acanthocephalan Corynosoma strumosum, Eustrongylides excisus, and larvae of a Contracaecum and an Anisakis species (Iranian Fisheries Research and Training Organization Newsletter, 11:4-5, 1996; Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 28, 1997; Shamsi and Dalimi, 1996; Shamsi et al., 1998; Shamsi et al., 1998). Ghayoumi et al. (2009) found that fish from Babol Sar harbour contained the intestinal helminths Corynosoma strumosum, Pronoprymna ventricosa, Contracaecum sp. larvae and Anisakis sp. larvae, diet being the main factor affecting diversity of the parasites. Varshoie et al. (2010) record the helminths Pseudopentagramma symmetrica (see above), Bunocotyle cingulata and Mazocreas alosae in this species from Iranian waters.

Clupeonella species are an important food fish for sturgeons (59.4% by weight of sevryuga (Acipenser stellatus) diet in the Middle Caspian), Sander (Percidae) and herrings and the Caspian seal. Predators consume 590 million kg of the three kilka species which themselves are the main consumers of zooplankton. Kilkas are a very important element in the life of the Caspian Sea (Badalov, 1972; Prikhod'ko, 1979b; Krylov, 1984). This species is taken to a lesser extent than other Clupeonella species because it is relatively sparse.

Economic importance

The bigeye kilka catch amounts to about 70 million kg a year in former Soviet waters of the Caspian by means of electric light. All three kilka species are caught by using underwater electric lights and fish pumps (Nikonorov, 1964) but in the case of the bigeye the effect is avoidance used to drive it to the bottom where it can be caught. Other kilkas are attracted to the light but the bigeye is a vertical migrator, avoiding sunlight (Prikhod'ko, 1979b). Light-assisted catches of kilkas damages young shad (Alosa) stocks which are an incidental catch (Zakharyan and Teruni, 1979). Catches in Iranian waters are only 6.84% of the total kilka take (Razavi Sayad, 1993b). The relative frequency of the bigeye kilka in Iranian catches was ranked second after anchovy kilka in 1990-1991 at 6.84%, increasing to 12.6% and 21.7% in 1997 and 1998 and then decreasing.

Omega-3 fatty acids from fish oil of this species has been tested as a dietary supplement and was found to relieve symptoms of dysmenorrhoea (Moghadamnia et al., 2010).

Conservation

Stocks in Iranian waters are said to be depleted. Kiabi et al. (1999) consider this species to be of least concern in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, abundant in numbers, widespread range (75% of water bodies), absent in other water bodies in Iran, and absent outside the Caspian Sea basin.

Further work

The biology of this species in Iranian waters needs to be elucidated.

Sources

Iranian material: CMNFI 1993-0167, 1, 93.0 mm standard length, Mazandaran, Caspian Sea (ca. 3649'N, ca. 5239'E); CMNFI 1993-0168, 2, 91.8-94.0 mm standard length, Mazandaran, Caspian Sea (ca. 3649'N, ca. 5239'E).

Genus Tenualosa
Fowler, 1934

This genus comprises 5 species found from the Indian Ocean to Indonesia and China. A single species enters rivers of southern Iran. The genus is defined by a series of characters listed below under Key characters. These fishes form part of local, artisanal fisheries throughout their range.

Tenualosa ilisha
(Hamilton, 1822)

Common names

صبور (= sobur, soboor, sobour, sabur, zobur, zabur, zamur or zomur, all variants of the same word), bari, barak; mahi-ye khor kuchiku (= small bone fish, at Abadan from www.abadan.com/abadanhistory.html, 15 March 1998).

[zoboor, soboor, sbour in Arabic; hilsa, Indian shad or river shad; palo, palla or pulla and tikki-palwar in Pakistan].

Systematics

Clupanodon ilisha was originally described from the Ganges estuaries in India. Formerly placed in the genus Hilsa Regan, 1917. Al-Hassan (1982), citing a personal communication from a Mr. Al-Abaychi in 1973, suggests that Shatt al Arab fish are distinct from those in Pakistan on morphometric and meristic grounds but no data have been published. Milton and Chenery (2001) used genetic and otolith chemistry data that provided strong evidence for a distinct stock in Kuwait, compared with stocks from India to Sumatra. Al-Hassan (1999) mentions that people in Basrah can distinguish two kinds of sobur, based on taste. One is the tastier and pricier Shatt al-Arab form and the other is the less desirable estuarine/sea form. This has not been confirmed by systematic studies. Jorfi et al. (2008; 2009) found differences between populations in Iran and Iraq using molecular techniques.

Key characters

This species is distinguished from other Indian Ocean clupeids by the upper jaw with a median notch, the anal fin ray count being less than 30 rays, a terminal mouth (lower jaw not prominent nor flared at the corners), scales in lateral series are not perforated posteriorly, last dorsal fin ray not filamentous, weakly developed lines (the fronto-parietal striae) on top of the head (usually covered by skin and not visible), gill rakers on inner arches straight not curled, a long head 28-32% of standard length, and 30-33 ventral scutes forming a keel along the belly, 15-18 being prepelvic and 11-15 postpelvic (Al-Nasiri and Al-Mukhtar, 1988a, 1988b; Marammazi et al., 1995).

Morphology

Dorsal fin with 4-5 unbranched rays followed by 14-16 branched rays, anal fin with 2-3 unbranched rays followed by 16-20 branched rays, pectoral fin branched rays 12-15 and pelvic fin branched rays 7. Lateral series scales 44-51. Gill rakers are fine and numerous, up to about 275 on the lower arch.

Iranian fish examined by Marammazi et al. (1995) from the Bahmanshir River in Khuzestan have 30-32 total scutes along the belly, 16-18 prepelvic scutes, 13-15 postpelvic scutes, 19-21 dorsal fin rays, 19-24 anal fin rays, 13-15 pectoral fin rays, 8 pelvic fin rays and 44-51 scales.

Sexual dimorphism

None reported.

Colour

The back is grey-blue, bluish to green and the sides are silvery with golden, purplish or pink highlights. The dorsal fin is grey, the caudal fin grey-blue with a silvery tinge and darkened margin, and the anal fin is light blue with some silvery tinges. Paired fins are hyaline. The area behind the gill cover in young fish and many adults have a dark blotch followed by a series of spots or blotches running along the upper flank, for a total of 6-7. The blotches may take the form of bars. The eye is yellow to red. Young have a bronze back, silvery flanks and a caudal fin margined in black.

Size

Attains 60.6 cm total length and 2.49 kg for females and 43 cm and 0.68 kg for males. A sample of 233 moribund fish from the Ashar Canal, a branch of the Shatt al Arab, Iraq examined by Al-Nasiri and Al-Mukhtar (1988a; 1988b) had a total length range of 70-152 mm. Hussain, Jabir and Yousif (1994) record fish migrating to the Shatt al Arab for breeding at 21-38 cm for males and 33-43 cm for females. Mature females in the Shatt al Arab weighed about 0.5-1.1 kg (Jabir and Faris, 1989). Fishes from Kuwait attained 57 cm (Al-Baz and Grove, 1995). Fishes from the Arvand, Bahmanshir, Karun and Dez rivers of Iran were 120-500 mm long (Marammazi et al., 1998; Ghafleh Marammazi et al., 2004).

Distribution

Reportedly found from the Red Sea and Persian Gulf through the Indian subcontinent to the Malayan Archipelago in some general works, or more narrowly from the Persian Gulf to Myanmar. It enters the Shatt al Arab and Tigris River, once as far north as Baghdad (Kanazawa, 1955), but the northernmost distribution today in Iraq is the Hawr al Hammar. Before the construction of dams on the Euphrates the migration was up to "Yaou" and "Meshkhau" and up to Qal`at Salih (3131'N, 4716'E) in the Tigris of Iraq (van den Eelaart, 1954).

The lower reaches of the Tigris and Euphrates rivers were connected by a channel to the Khor Al-Zubair in Iraq during 1983. As a consequence the Khor became oligohaline (at less than 10) rather than hypersaline (at more than 40), becoming an estuary with heavy reed growth. The catch of sobour in the Khor by 1997 exceeded that in the Shatt al Arab and may involve diversion of stocks from the original habitat of the Shatt (Hussain, 1997).

In Iran, it is recorded as far north as the Gargar Shoteit on the Dez River (Marammazi, 1994). Hussain, Jabir and Yousif (in litt., 1995) record this species from the Shatt al Arab in Iraq and the Bahmanshir, Jarrahi, Zohreh and Hilleh rivers in Iran. Marammazi (1994) and Marammazi et al. (1998) report this species from the Arvand, Bahmanshir, Karun and Dez rivers. Ghafleh Marammazi et al. (2004) record it from the Zohreh, Bahmanshir, Arvand and Karun rivers in Iran. It may be found in the Hormuz basin but this has not been verified with specimens.

In the sea, they are found from Bushehr around to Kuwait in coastal waters (Blegvad and Lppenthin, 1944; Hussain, Jabir and Yousif, in litt., 1995).

Zoogeography

Al-Hassan (1982) mentions a study comparing a population of this species from Basrah, Iraq with one from Pakistan and finding significant meristic and morphometric differences, perhaps indicative of distinct stocks.

Habitat

Sobour enter the Shatt al Arab in February and March during high tides and feed there until the fall according to a study by Al-Nasiri and Al-Mukhtar (1988a; 1988b) working on fish taken from the Ashar Canal, Basrah, Iraq. van den Eelaart (1954) reports that most fish enter the Shatt al Arab in April during the last and first phase of the moon and anecdotal reports indicate the end of March to be the peak period of entry. They ascended into the Hawr all Hammar and from there into the Euphrates as well as into the Tigris (van den Eelaart, 1954). Significant numbers were recording as entering the recovering Hawr al Hammar in 2005-2006 (Hussain et al., 2006). Small specimens (50-100 mm) were observed in the east Hawr al Hammar in June 2005 and July 2006 (www.iraqmarshes.org, downloaded 29 August 2005; N. A. Hussain, in litt., 2006). In mid-April sbour were found below the Yaou and Moshkhab regulators which formed the limit of their migration on the Euphrates in the early 1950s. The limit in the Tigris was beyond Amara. The main spawning grounds in the Euphrates were probably somewhere between Shinafiya and Samawa and in the Tigris between Amara and Qalat Saleh.

The last ones leave the Shatt in July and fry are found in the rivers of Iraq at the end of the June. Hussain, Jabir and Yousif (1994) record sobour ascending the Shatt al Arab during March with a continuing migration upstream through April to July for spawning and a return migration to the sea during August to October. Al-Hassan (1993) notes that local people believe that sobour ascend the Shatt al Arab during spring to marshes north of Basrah for spawning, suggesting that they are the fluvial anadromous type. Al-Hassan (1999) considers they migrate to the sea in September-November, when they are landed in Kuwait, and they then migrate to the Iranian coast during December-January. Males and females move upriver in separate groups according to Iraqi fishermen (Al-Hassan, 1999).

Jorfi et al. (2008) suggest, based on molecular studies, that a population in the Persian Gulf chooses the Karun River for spawning and migrates via the Bahmanshir River, while others migrate up the Tigris and Euphrates rivers in Iraq via both the Bahmanshir and the Arvand rivers.

Blegvad and Lppenthin (1944) mention this species on sale at Khorramshahr on 28-29 April. The spawning migration in Iran occurs in spring (I. Sharifpour, in litt., 1991). It is only found in the Zohreh River in spring and summer (Marammazi, 1994).

They may be found in deep water, over 18 m, or in shallows, on their spawning migration. Large concentrations of sobour occur below dams blocking their migration. Young occur in side branches of the Shatt al Arab near food, shelter and the spawning grounds (Hussain, Jabir and Yousif, in litt., 1995).

This species occurs in river estuaries and coastal waters and appears to be restricted to the northern end of the Persian Gulf because this is the only part with large spawning rivers (Hussain, Jabir and Yousif, in litt., 1995). These authors also suggest that an anadromous stock from the Shatt al Arab migrates to warmer waters off Bushehr during January, February and March. At the same time there is a winter decline of Kuwaiti stocks. There may also be a marine stock inhabiting coastal waters of Kuwait since larvae have been found in Kuwait Bay during June and November and catches are made in the Bay year round.

Biogenic and anthropogenic sources were noted for the hydrocarbons in this species from the Shatt al Arab; n-alkanes attained 31.11 g/g and hydrocarbons 10.91 g/g, the highest for the fish species studied (Al-Saad et al., 1997). The fat content of this shad is a factor in these high levels (Al-Saad, 1990).

Hussain (1997) notes that the changing conditions in the Khawr az Zubayr, which became oligohaline from hypersaline after it was connected to the Tigris-Euphrates basin by the Shatt al Basrah Canal. In 1994 fishermen began catching sbour in the Khawr az Zubayr and by 1997 the numbers caught exceeded the catch in the Shatt al Arab.

Migrations in the Indus River of Pakistan (Islam and Talbot, 1968) may last over 7 months and the migration up the Ganges River extends over 1287 km. Fish may move as much as 70.8 km in one day and may jump out of the water on the migration.

Age and growth

In the Bahmanshir River, Iran most fish are 4-5 years old. The minimum total length and age at maturity are 26.2 cm, 200 g and 2 years for males and 32.18 cm, 450 g and 3 years for females. Von Bertalanffy growth parameters in Iranian females are L = 57.78 cm and K = 0.282 and in males 46.37 cm and 0.252 (Marammazi, 1995; Iranian Fisheries Research and Training Organization Newsletter, 12:5, 1996; Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 53-54, 1997).

Hashemi et al. (2009) studied fish landed at Hendigan and Abadan and recorded L as 42.81 cm, K was 0.9, M was 1.37, F was 2.41, Z was 3.78 and E was 0.64. Y'/R was 0.048 and B'/R was 0.19, exploitation rate (U) was 0.61, annual stock at the beginning of the year (P) was 7615 t, annual standing stock (b) was 1927 t and MSY was 3642 t. The stock was overfished.

Hashemi et al. (2010) studied 9317 fish from landings at Abadan and Hendijan. Size range was 20-39 cm. The von Bertalanffy growth parameters were L = 43.32 cm, K = 0.78 yr-1, Φ' was 3.16 and t0 was -0.18. Mortality rates were M = 1.29 and Z = 4.53, and fishing mortality (F) was 3.24 yr-1. The exploitation rate (E) was 0.72 and the stock was overfished. Values of the sizes where the probability of capture was 50% (L50) and 100% (L100) were 22.3 and 28.5 cm TL respectively. Fish were recruited to the fishery at a mean size of  L100 = 22.3 cm. The relative yield per recruit (Y'/R) was 0.062, relative biomass per recruit (B'/R) was 0.12 and exploitation rate (U) was 0.76. The values for annual catch, total annual stock, standing stock and maximum sustainable yield were 4645 t, 6635.71 t, 1433.64 t and 3274.19 t respectively. The fishing pressure must be reduced from 3.24 yr-1 to about 0.97 yr-1for this population to be adequately managed. Another study apparently based on the same or similar samples (Hashemi Seyed et al., 2010) found slightly different parameters: L = 42.81 cm, K = 0.0 yr-1, t0 = -0.25. Z = 3.78, M = 1.37, F = 2.41, E = 0.64 and the values for annual catch, annual average standing stock and maximum sustainable yield were 7615 t, 1927 t, and 3624 t respectively.

Roomiani and Jamili (2011) examined fish landed in Iran from a northern Persian Gulf fishery. Growth was isometric. Maximum total length was 43 cm and weight 949 g. von Bertalanffy growth parameters were  L = 42.74 cm total length, K = 0.77 and t0 = -0.21 years-1. Total mortality (Z) was 2.55 years-1, natural mortality was 0.75 years-1, fishing mortality was 1.8 years-1, and exploitation rate (E) was 0.7 years-1, and parameters indicate overfishing. Maximum sustainable yield was calculated to be 2653 t.

Al-Nasiri and Al-Mukhtar (1988a; 1988b) give a length-weight relationship of W = 3.9 x 10-6 L3.16 or log W = 3.16 log L-5.4 for fish aged at 0+ from the Ashar Canal at Basrah. The mean condition factor was 0.87. Fishes in the Shatt al Arab are in age groups 5 to 6 for the period May to August (Hussain et al., 1991). In contrast, a later study on the Shatt al Arab fish showed there are 5 age groups and the second and third age groups dominate in catches (Hussain, Jabir and Yousif, 1994). In this latter study, Shatt al Arab fish mature at 25 cm for males and 33 cm for females, similar to an Iranian study (see below). The length-weight relationship was log W = -4.7074 + 3.0479 log L for females and log W = -4.5802 + 3.0193 log L. Condition factor gradually increased with length groups in males, peaking at 32-33 cm followed by a sharp decline while females had a nearly stable condition factor from 34 to 43 cm. Mohammed et al. (2001) gave a von Bertalanffy growth equation as L = 60.47 cm and a condition factor of 0.32, slower growth than in Indian and Bangladesh populations and probably maturing later.

Amodeo (1956) gives lengths of 25 to 35 cm for fish caught in the Shatt al Arab on their spawning migration. Young grow rapidly, 4.3 cm in October-November. Most fish on the migration in the Indus River were in age groups 3 and 4. Life span is up to an estimated 7 years with maturity as early as 1 year. Jawad et al. (2004) found haematocrit level to increase with body length up to 40 cm after which it decreased, males showed higher levels than females, and levels were higher pre-spawning than during spawning and increased slightly post-spawning, a general correlation with fish activity.

Al-Baz and Grove (1995) studied fish taken from Kuwait fish markets. Females dominated the catch, male:female ratio being 1:2.4, perhaps because the sexes moved in different schools. The smallest mature female was 34.4 cm and 50% of the females are mature at 41.5 cm. They estimated natural mortality (M) based on von Bertalanffy growth parameters (L and K) and mean annual water temperature as log M = -0.0066 -0.279 log L+ 0.6543 log K + 0.4634 log T. The length-weight relationship was W = 0.011 L2.983 for males and W = 0.007 L3.104 for females. Growth in the sexes follows different patterns. Five age groups were detected using otoliths and fish were fully recruited to the fishery at 3 years of age. von Bertalanffy growth parameters were L = 52.70 cm and condition factor (K) = 0.28 per year while using Allen's method they were L =52.50 cm and condition factor (K) = 0.36 per year Growth curves were given. Annual total mortality was estimated to be 1.2 using the K value of 0.36. A fishing mortality was calculated to be 0.8 per year.

Food

The Ashar Canal study found them to feed on phytoplankton such as dinoflagellates and diatoms and on zooplankton, mainly copepods, as well as their own young. The sieve-like gill rakers are used to strain out planktonic organisms without selection. Presence of some sand grains indicates that feeding can occur on the river bed. Feeding intensity may decrease or cease on the spawning migration and is very high after spawning. The Bahmanshir fish feed principally on copepods and diatoms. Shatt al Arab juveniles feed mostly on filamentous algae and diatoms with some organic matter, fish eggs and zooplankton while adults have empty stomachs on the spawning migration (Hussain, Jabir and Yousif, in litt., 1995). In the Indus River, the newly hatched larvae and juveniles graze for five to six months in fresh waters before they migrate to the sea (www.jang-group.com/thenews/feb2003-daily/18-02-2003/business/b2.htm, downloaded 18 February 2003).

The prime food in the sea off the Iranian coast is phytoplankton, principally Bacilliariophyta followed by Pyrrophyta. Zooplankton is also taken (Nasri Tajan et al., 2008).

Reproduction

The spawning migration depends on the flood regime of the rivers. Turbid water and fast current are probably stimulants to egg deposition. The sbour depends on river-edge vegetation for egg deposition. Spawning grounds in Iraq are probably located near the beginning of the side branches of the northern sector of the Shatt al Arab, 120 km from the sea (Hussain, Jabir and Yousif, 1994). This species is gonochoristic (Blaber et al., 1997). Males may ascend the river before females but females become dominant in Indian populations. Males dominate in March in the Shatt al Arab and the sex ratio reaches equilibrium in the spawning months of May-July (elsewhere in the same communication spawning is given as June to August) (Hussain, Jabir and Yousif, 1994; Jawad et al. (2004). Spawning may occur more than once in a season in India. This has not been demonstrated for Iran but could occur. The gonadosomatic index for fishes in the Iraqi Shatt al Arab indicates peaks in March-May and July-August, suggesting two spawnings (Hussain et al., 1991) although a later report (Hussain, Jabir and Yousif, 1994) gives spawning as June to July and July to August as evidenced by two modes of juveniles found in September. Sex ratio is equal during this period. All females entering the Shatt al Arab were mature with smallest female being 33.0 cm long. Males less than 25.0 cm were immature, the population reaching 100% maturity at 31-32 cm (Hussain, Jabir and Yousif, 1994). The Kuwait fish studied by Al-Baz and Grove (1995) indicated spawning between May and July with a peak in June.

Fecundity in the Indus River population was estimated to be up to 2,917,000 eggs per female, egg diameters reached 0.89 mm, and the hatching takes place in about 23 to 26 hours (http://www.jang-group.com/thenews/feb2003-daily/18-02-2003/business/b2.htm, downloaded 18 February 2003). Estimates for the Hooghly River of India reach 13,230,500 eggs per female (Al-Hassan, 1993). Fecundity in the Shatt al Arab ranges between 444,960 and 1,616,560 eggs for fish 33.0-41.5 cm total length although 2 fish 37.3 and 2 fish 39.0 cm total length had a range in egg numbers of 109,000-233,840, showing that great variations in fecundity occur between individuals; possibly some fish had partially spawned before capture (Jabir and Faris, 1989). This latter study gave a relationship between absolute fecundity and total length as F = 1.3699 L3.6681 and log F = 0.1367 + 3.6681 log L and between fecundity and weight F = 302.8214 W1.2087 and log F = 2.4812 + 1.2087 log W. Fecundity increased significantly with body weight, ovary weight and total length. Relative fecundity (ova/gramme body weight) varied from 737 to 1721, mean 1216.

Hatching can occur within one day at an average temperature of 23C. Eggs, larvae and young are found on the spawning grounds but with growth the young move into estuarine and foreshore areas during winter months. Hussain, Jabir and Yousif (1994) record the appearance of juveniles from the northern Shatt al Arab from June to November. Adults return to their original habitat in the sea after spawning. There is some evidence for freshwater resident populations in India which migrate upriver to spawn but do not descend to the sea.

The Bahmanshir fish are thought to spawn from April to July. Only adults enter the Bahmanshir (Iranian Fisheries Research and Training Organization Newsletter, 12:5, 1996). Absolute fecundity of fish from the Arvand, Bahmanshir, Karun and Dez rivers ranges from 374,892 to 1,954,144 eggs for total lengths of 380 to 500 mm respectively and is related to age. Ova with diameters 0.64-0.795 mm were released spontaneously in a study of this fish in Khuzestan province, in several batches along its migration route (Ghafleh Marammazi et al., 2004). Spawning begins on entry to the Bahmanshir and Arvand rivers in Khuzestan in April, continuing to September and the end of their migration at the cities of Shushtar and Dezful higher upriver. Males enter these rivers first in March, followed by females in April (Ghafleh Marammazi et al., 2004).

Parasites and predators

None reported from Iran other than nematode larvae by Ebrahimzadeh and Nabawi (1975) for fish from the Karun River.

Economic importance

The Ashar Canal study cites 996,308 kg reaching the Ashar fish market from October 1975 to June 1977 (see also Sharma, 1980). The catch landed at Fao on the Shatt al Arab estuary of Iraq was 6576 t in 1990-1991 (L. A. J. Al-Hassan, in litt., 1995; however this seems much too high although the estimate is from the Food and Agriculture Organization). This species forms the most important commercial fishery in the Basrah region of southern Iraq, average catches being 491.086, 319.661 and 267.988 t in 1977, 1978 and 1979 respectively (sic, Jabir and Faris, 1989). There is a drift-net and stake-net ("hadra") fishery in the sea by Kuwait in Kuwait Bay and around Falaikah Island (Al-Baz and Grove, 1995).

The fishing season on the Tigris-Euphrates is March to August with a peak in April, or late April to early June (Jabir and Faris, 1989) or to November (Ali et al., 1998). van den Eelaart (1954) gave the fishing season for this species as March-August (peaking in April) in rivers, and March-May (peaking in April) in Hawr al Hammar, Iraq. Fish are caught at the mouth of the Shatt al Arab as they enter the river with stationary gill nets, drifting gill nets, in "mailan" and "odda" traps from March to August. The catch averaged 150-180 kg per ten odda and in March 1953 the total catch at the mouth of the Shatt al Arab was about 25,000 kg (Amodeo, 1956). Large fish are only caught in the summer (Al-Hassan, 1999).

The catch at Abadan from February to November in 1943 was about 401.42 t and from January to June about 336.67 t (Pillay and Rosa, 1963). This species is seen on markets at Ahvaz, Khuzestan in November but these are sea-caught fish. Marjan Iran Company was selling 600-800 g fish for U.S.$1.40/kg, 800-1000 g fish for U.S.$1.60/kg, 1000-1200 g fish for U.S.$1.70/kg, and 1200 g and larger fish for U.S.$1.80/kg in August 2003 (http://groups.yahoo.com/groups/hilsa/message/25). The catch in Khuzestan province in 2000 was 2688 t (Ghafleh Marammazi et al., 2004) and  in 2006 was 4989.83 t (about 15% of Khuzestan's total commercial fish landing) (Roomiani and Jamili, 2011). The catch in Khuzestan Province in 2008 was 4645 t (Hashemi et al., 2010).

These fish are caught with traps, weirs, gill nets and other devices in rivers on the spawning migration. They are excellent eating until spawning occurs after which they lose their flavour. However this species has been implicated in clupeotoxic poisoning. Hindi et al. (1996a) give the chemical composition of flesh of this species as 66.41% moisture, 12.12% fat, 18.72% protein and 1.98% ash, indicating a valuable food fish characterised as fatty. Hindi et al. (1996b) give chemical indices for assessing fish freshness according to the month of capture and marketing (pH 6.06, total volatile nitrogen bases 15.32 mgN/100g fish, thiobarbituric acid 1.35 mg, and free fatty acids 1.33%). Salari and Sadough (2009) compared heavy metal (Cd, Pb, Cu, Co, Ni) content in muscle, liver and gill tissues of fish from the Karun River and found levels less than those considered dangerous in Iran.

In Pakistan, the Indus River fishermen number between 8,000 and 9,000. Jafri (1994) reviews the Indus fishery which had yields up to 2694 mt. It is the most important Indo-Pacific shad species. The failure of the Indus River fishery in 2003 through drought resulted in Iranian fish being flown to Pakistan for marketing there at rupees150-400 per piece (www.jang-group.com/thenews/feb2003-daily/18-02-2003/business/b2.htm, downloaded 18 February 2003).

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food, in aquaculture and in textbooks.

Conservation

Hussain, Jabir and Yousif (in litt., 1995) report a decline in catches over the previous two decades in the Shatt al Arab. Al-Nasiri and Al-Mukhtar (1988a; 1988b) mention that fish enter the polluted Ashar Canal, a side tributary of the Shatt al Arab, during high tide when waters are diluted. A low tide in October resulted in severe oxygen depletion and fish suffocated. Das et al. (1977) found samples from the Ashar fish market in Basrah to be contaminated with hydrocarbons, emitting a kerosene smell and being unfit for human consumption. Al-Saad (1990) found petroleum hydrocarbon residues to be high in Khawr az Zubayr fish at 40.6 μg/g as this species is one that accumulates fat. Evidently, overfishing and pollution are major factors in the conservation of this species, to which must be added variations in freshwater flow and quality from the marshes and Tigris-Euphrates through human processes.

Further work

The migratory habits and ecological requirements of this food fish need to be examined in more detail for Iranian waters.

Sources

Some aspects of the biology of this species were based on Pillay and Rosa (1963) and Al-Hassan (1993) writing mostly on Indian and Pakistani populations. Specimens on markets in Ahvaz, Khuzestan examined.

Iranian material: CMNFI 1991-0153, 1, 243.3 mm standard length, Khuzestan, Zohreh River (no other locality data).

Comparative material: BM(NH) 1875.1.14:11-13, 3, 118.8-135.8 mm standard length, Iraq, Tigris River (no other locality data); BM(NH) 1920.3.3:178-182, 6, 103.3-132.4 mm standard length, Iraq, Basra (3030'N, 4747'E); BM(NH) 1989.1.13:1-3, 3, 53.9-59.9 mm standard length, Iraq, Khawr az Zubayr (no other locality data); BM(NH) 1989.1.13:4-5, 2, 66.6-69.8 mm standard length, Iraq, Khawr az Zubayr (no other locality data).

Brian W. Coad (www.briancoad.com)