Freshwater Fishes of Iran

Species Accounts

Description
and
Petromyzontidae to Chanidae

Revised:  16 July 2012

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 Løppenthin (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.

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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Adult

Ammocoete

Disc

Adult, courtesy of Afshin Afzali, University of Tehran

Adult, Shirud River, photograph courtesy H. Nazari

Siardarvishan River, April 2010, courtesy of K. Abbasi

Adults, Shirud River, photograph courtesy H. Nazari.

Disc, photograph courtesy H. Nazari

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) (Holčík, 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; Holčík and Oláh, 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 6-11°C. 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, Holčík (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, Holčík (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 10-11°C and moved through channels where the current was strongest. Spawning begins at 15-16°C, usually in early June but sometimes at the end of March through to the beginning of July, and temperatures during spawning are usually 15-23°C. 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 17-23°C. 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 11.0-21.25°C. The most intensive migration was at night (peaking at 2100 and declining to 0300 hours) at 16°C (34.4% of the run). About 75% of the run had  passed by the time water temperature reached 16-17°C. Migration stopped when temperature reached 21°C. 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) 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.

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 (Holčík and Oláh, 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 Holčík (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 (37º35'N, 49º09'E); CMNFI 1970-0514, 33 ammocoetes, ? mm total length, Gilan, Shafa River estuary (37º35'N, 49º09'E); CMNFI 1970-0515, 18 ammocoetes, ? 25-98 mm total length, Gilan, Shafa River estuary (37º35'N, 49º09'E); CMNFI 1970-0534, 30 ammocoetes, ? mm total length, Gilan, Shafa River estuary (37º35'N, 49º09'E); CMNFI 1970-0535, 14 ammocoetes, ? mm total length, Gilan, Shafa River estuary (37º35'N, 49º09'E); CMNFI 1970-0545, 1 adult? see photo?, ?mm total length, Gilan, Safid River (37º01'N, 49º38'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 (37º35'N, 49º09'E); CMNFI 1970-0585, 3 adults, 406.0-455.0 mm total length, Gilan, Nahang Roga River (37º28'N, 49º28'E); CMNFI 1971-0327A, 1 adult (part of trunk), Gilan, Shafa River estuary (37º35'N, 49º09'E); CMNFI 1979-0787, 11 adults, ?mm total length, Gilan, Nahang Roga River (37º28'N, 49º28'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 (37º26'N, 49º40'E).

Carcharhinidae
 

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Upper and lower tooth

BM(NH)1924.10.1:1, Tigris River at Al Karradah near Baghdad,
photograph by Brian W. Coad

BM(NH) 1874.4.28:9, Tigris River near Baghdad, photograph by Brian W. Coad

Common names

kooseh, kuseh, kooseh-kuli, sag mahi (= dog fish).

[kosetch or kossage, jarjur in Arabic; bull shark].

Systematics

Carcharhinus leucas was originally described from the Antilles.

A number of shark species have been reported as entering rivers of the Tigris-Euphrates basin including Iranian tributaries (Günther, 1874; Day, 1875-1878; Sykes, 1902; Kennedy, 1937; Hunt, 1951; Khalaf, 1961; Mahdi, 1962; Zorzi, 1995; and others). The species appeared under such names as Carcharhinus gangeticus (Müller and Henle, 1839), Eulamia (= Carcharhinus) lamia (Blainville, 1820), and Carcharhinus menisorrah (Valenciennes in Müller and Henle, 1839). A recent revision of carcharhinid sharks by Garrick (1982) cites only Carcharhinus leucas from fresh waters of the Tigris-Euphrates basin and Compagno (1984) concurs. Coad and Papahn (1988) also list specimens which confirm this species to be present.

Key characters

This is the only shark species commonly encountered in Iranian fresh waters and can be recognised by the 5 gill slits, upper caudal fin lobe larger than lower, and the arched mouth armed with teeth on the underside of the head. Distinction from other sharks is given in Compagno (1984).

Morphology

The snout is very short, rounded and ends bluntly. Its length is less than the distance between the nostrils and much less than the mouth width. There are 12-14, usually 13, teeth on each side of a median tooth in the upper jaw and 12-13, usually 12, teeth on each side of a median tooth in the lower jaw. Teeth are heavy, broad, almost triangular, erect near the jaw symphysis but becoming slightly oblique and more concave or notched nearer the mouth corners. The teeth are strongly serrated, more so near the base, and upper teeth more so than lower teeth.

The first dorsal fin lies over or just behind the level of the axil of the pectoral fin. The apex of the first dorsal fin is pointed to somewhat rounded. The second dorsal fin is high, has a short posterior lobe and lies just over the level of the anal fin origin. Pectoral fins are broad and their tips are narrow and pointed. There is no interdorsal ridge (the back is smooth between the dorsal fins). The upper precaudal pit is well-developed while the lower pit is weak.

Sexual dimorphism

Males bear claspers. The pelvic fins are partially modified into grooved, rod-like structures which are held together to form a tube and are used in mating. They are not used to clasp the female but as an intromittent organ. Females are larger than males.

Colour

Fin tips are dusky to black, particularly in young. There is no other obvious colour pattern although the back is darker than the belly, being bluish, grey or brown. Fins are similar in colour to the neighbouring body.

Size

Attains 3.24 m (Garrick, 1982), 3.40 m (Carpenter et al. 1997), rarely to 4.0 m and an estimated weight of over 600 kg (McCord and Lamberth, 2009). Fish in Iranian fresh waters have been estimated as up to 2 m in length but naturally circumstances were not always favourable for an objective and detached size judgment.

Distribution

Sharks have long been known to enter fresh waters in the Tigris-Euphrates basin. Zorzi (1995) records a book by Pausanias, "Guide to Greece", written in the late second century which refers to sharks in "the Euphrates...., which fatten monsters as man-eating as any in existence".

One of the earliest distributional records is found in the Arabic work "Wonders of Creation" by Zakariya al-Qazwini published in 1263 A.D. and later translated into Persian. The sharks were found at Basrah on the Tigris River in what is now Iraq and were cited as formidable because of their voracity and teeth like the points of spears. Shark attacks still occur at Basrah (Coad and Al-Hassan, 1989).

Subsequently reported in the Tigris River above Baghdad about 850 km from the sea (Günther, 1874; Kennedy, 1937) before dams were built. Sykes (1902) saw sharks in the Ab-e Gargar (Karun River in Iran) at Shushtar 420 km from the sea, Wilson (1942) reporting on events in 1908 records sharks from between Shushtar and Ahvaz and near Shushtar, Blegvad and Løppenthin (1944) report then from Khorramshahr, and Hunt (1951) reported them from the Karun River, Khowr-e Bahmanshir and Shatt al Arab (Arvand River). Coad and Papahn (1988) report sharks at Ahvaz on the Karun River about 275 km from the sea as well as further up river at Shushtar and down river in the Khowr-e Bahmanshir.

Zoogeography

This shark is found world-wide in warm temperate to tropical seas and is reported from fresh waters in Africa, Asia, Australia and the Americas.

Habitat

This is a shark of coastal waters such as harbours, bays and estuaries but unusually it will penetrate far up rivers, as far as 4000 km up the Amazon River. It is said to be a sluggish bottom dweller except when attacking prey and in the sea may be found down to at least 150 m although usually at less than 30 m. They are said to invade the Khowr-e Bahmanshir and Karun River of Iran from July to September when freshwater flow is at a minimum and tidal penetration of salt water is at its highest. However they do travel well beyond tidal influence in Iran. Local people along the Bahmanshir River near Tangeh Se in Khuzestan maintain that it is dangerous to swim there because of these sharks. They are occasionally trapped in nets set for Tenualosa ilisha and may be caught on hooks. They are not as common as in the past (N. Najafpour, pers. comm., November 2000).

Age and growth

Maturity in males is attained at 1.60-2.25 m and in females at 1.80-2.30 m. Mature fish are about 6 years old and life span is up to about 14 years.

Food

Food is a wide variety of fishes including tunas, small sharks, and rays, as well as crabs, shrimps, molluscs, cephalopods, sea urchins, turtles, sea birds and mammals. Diet in fresh water has not been investigated in Southwest Asia although Blegvad and Løppenthin (1944) reported that sharks station themselves under the date palms at Khorramshahr to eat the falling dates!

Reproduction

Birth size is about 56-81 cm and takes place in estuaries and river mouths. Females may contain up to 13 embryos and the gestation period is 10-11 months. This species is known to breed in fresh waters, such as Lake Nicaragua in Central America, but there have been no reports of reproduction in the Tigris-Euphrates basin.

Parasites and predators

None are reported for Iran.

Economic importance

This shark has a considerable impact on people using water directly in Khuzestan. A number of severe injuries and fatalities have been reported in fresh waters through shark attacks. The first comprehensive report in modern times was by Hunt (1951) although accounts date back to the thirteenth century (Coad and Papahn, 1988). The latter summarize recorded attacks and add new ones for a total of 34 in the period 1941-1985, of which about half were fatal. Additionally Wilson (1942) reports a woman taken by a shark while drawing water between Shushtar and Ahvaz and a 9 foot (= 2.8 m) near Shushtar which killed two boys and a girl. These Iranian records are a significant proportion of freshwater attacks worldwide, about 28%. A number of soldiers were apparently victims during the Iran-Iraq war but no records have come to light. Men, women and children are attacked as well as horses and sheep, only the massive water buffalo is said to be safe. Many minor attacks and narrow misses are probably not reported. Attacks are said to have declined in recent years since shark oil is no longer used to caulk boats but this is probably a local legend. People were attacked while swimming, paddling, bathing, washing vehicles or fishing. There was no apparent triggering factors for the attacks as victims were dressed in various colours and types of clothing, engaged in various activities and environmental conditions where known varied between attack sites.

Freshwater shark attacks have even appeared in a novel "Harem" by Mossanen (2002).

In other parts of the world, this species has been used for its flesh and fins, as leather, for its liver oil and for fishmeal. Sharks can be eaten by Muslims if "reliable experts confirmed that shark fell into the category of cartilaginous and scaly fish" (http://netiran.com:80/news/IRNA/html/950216IRGG13.html) which appears to be so (netiran.com/news/IranNews/html/95021814INPL.html).

Conservation

This shark appears to still be common in Iranian fresh waters judging from the attacks reported over the past 50 years or more and no conservation measures are needed (or likely to be acceptable to the local population).

Further work

The biology of this species in fresh water is unknown for Iran and Iraq and should be thoroughly investigated as a real hazard to those using rivers of Mesopotamia. Are the sharks permanent residents or seasonal visitors? Detailed records of attacks should be kept and analyzed in an attempt to determine any triggering actions. It may prove possible to make recommendations for use of water resources so as to avoid shark attacks in future.

Sources

Garrick (1982) and Compagno (1984, 1988) for general anatomy and biology.

Comparative material: BM(NH) 1874.4.28:9, 1, ca. 76.8 cm total length, Iraq, Tigris River near Baghdad (ca. 33º21'N, ca. 44º25'E); BM(NH) 1924.10.1:1 1, (head only, recorded length 4 ft 1 inch = 1.25 m), Tigris River at Al Karradah near Baghdad (33º17'N, 44º23'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):-

 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:-

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 Doré (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 Doré (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 Doré, 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 Doré, 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 Holčík (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 Doré, 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'Illustré, 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'Illustré, 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 (8-12°C) 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 4°C 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 4-8°C. 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 -3°C 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 Doré (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 0-2°C.  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)

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 -3°C (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.

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.

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
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 güldenstädti, 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 Holčík (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 or 2n=247 ± 7 (Klinkhardt et al., 1995).

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. 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 2.3-24.8°C 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 20°C. Reproduction in the Kura ceases when temperatures reach 26°C. 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 8-18°C (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 1-4°C, 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 9-15°C. 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 12-15°C. The late spring race migrates to spawning sites in May-June, spawning in July-August at 19-22°C. 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 9-13°C.

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

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, šep 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 Holčík (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 (Holčík, 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=118 ± 2 (Klinkhardt et al., 1995) or 2n=118 ± 3 (Nowruzfashkhami et al., 2000). 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 6.2-13.0°C while the fall run is at 12.0-17.9°C. Males predominate over females by 3-6 times. Spawning occurs in April-May at water temperatures of 10-25°C and normal development occurs between 11.0 and 17.1°C. 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 Holčík (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. (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 Holčík (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 Holčík (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 Holčík (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).

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. 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 Holčík (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 4.1-28.0°C 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.

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 15-25°C, mainly at 17-23°C, at higher temperatures than A. gueldenstaedtii (8-18°C). 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 26-30°C. 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 19-21°C. 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 29°C, 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 (16.1-18.0ºC 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 15-18ºC 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 24ºC 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 increase in growth efficiency and survival rate of larvae fed Daphnia magna bioencapsulated with probiotic bacilli (Faramarzi 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); ultrastructure and osmoregulatory function of larval kidneys (Taghizadeh Rahmat Abad et al.,  2011); on Lactobacillus species from the guts (Ghanbari and Jami, 2011b); sex chromosomes were not differentiated sufficiently using AFLP to identify males and females at an early life stage (Yarmohammadi et al., 2011);  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.

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 Güldenstädt, 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=146±6 (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 more than 80 kg. Sternin and Doré (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 4-24°C, in winter 7.5-10.5°C and 11.0-24.0°C in summer and fall, with an absolute range of 2.4-29.5°C. Water temperatures below 6°C 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.

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 16-22°C. 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.

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 10°C and peaks at 18°C, 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 15-29°C. 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 15-26°C. Incubation takes 44-80 hours at 20-28°C. 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)

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 (Holčík, 1989). Acipenser brandtii Günther, 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).

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 Doré (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 Doré (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 5.6-29.3°C 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 0.5-30°C and the spawning migration at a range of 6-21°C. The highest densities in the southern Caspian Sea occur at 22-29ºC, feeding in winter at 10-12ºC (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 9-11°C.

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 9-17°C 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. 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). Sepahdari et al. (2010) found deleterious changes in liver tissues n fish fed a diet containing aflatoxin B₁. Alizadeh et al. (2011) studied seasonal changes of blood serum ions in brackish water, a proposed culture medium, at Bafgh in Yazd Province. 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. 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). Yarmohammadi et al. (2011) found sex chromosomes were not differentiated sufficiently using AFLP to identify males and females at an early life stage.

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

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 24ºC and a salinity of 12.5‰ the fish reached 250 g with a survival rate of 60%, after six months at 16ºC 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 (45°09'N, 29°41'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.

Anguillidae
 

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Iranian material: CMNFI 1979-0142, 11, 70.5-98.5 mm standard length, Hormozgan, Baghu River (27º17'N, 56º28'E) (Coad, 1981b).

© Brian W. Coad (www.briancoad.com)