Species Accounts - Acipenseridae - Acipenser

Revised:  15 May 2008

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 Il'in, 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 (Safari et al., 2007).

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).

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 Il'in, 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) 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 Il'in, 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, 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.

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 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 daizinon. 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).

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 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) 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. 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.

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. 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).

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.

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 including the Safid River (to "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 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, Tajan, Babol, Haraz, and Safid rivers, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea by Kiabi et al. (1999) and in the Safid River by Abbasi et al. (1999). 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, weight s19.95 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).

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)

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).

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.

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.

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 ideal stocking densities in tanks  (Derakhshandeh Ghazi Mahale, 1997); rearing using earthworms (Kazerooni Monfared, 1995); protective immunity against infectious diseases using antigens from Aeromonas hydrophila which causes septicaemia (Kalbassi et al., 2000); haematological variables in juveniles and adults at different water temperatures (Pourgholam and Saeidi, 2000); purification and partial characterisation of serum immunoglobulins (Kalbassi et al., 2003); physiological studies on the liver oxidase system (Karimzadeh et al., 2003); on clove oil having no significant difference with MS222, another anaesthetic used in fish farms (Abtahi et al., 2002; 2003), studies on stress during transport and confinement of brood stock as evaluated using blood samples (Bahmani et al., 2000; Bahmani and Oryan, 2004); the identification of fatty acids in the flesh and the effects of long-term freezing on them (Hedayatifard and Moini, 2004); histology of the gut from hatching to 56 days (Pahlavan Yali et al., 2004); the effect of the timing of first feeding with live food on growth and survival of larvae (Kordjazi et al., 2004); 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); effect of temperature on fertilisation percentage achieved by broodstock (16.1-18.0ºC was optimal)(Hoosini Najd Gerami and Hajimoradlu, 2004);  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); the enhancement effect of ozone and physical treatment on the hatching rate of eggs (Ghomi et al., 2003); 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 and Nazari, 2006); dietary levels of fat and protein effecting growth and chemical composition of fingerlings (Ebrahimi et al., 2004; Mohseni et al., 2007); establishing blood serum parameters as tools in disease prognosis and control (Shahsavani et al., 2006); on optimum feeding rate for fingerlings (Yousefpour Pirbazari et al., 2000), 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); 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 use of rotifers (Brachionus plicatilis) in conjunction with Artemia nauplii as food for larvae (Haddai Moghadam, 2006); feeding formulated diets to larvae and juveniles in hatchery rearing (Pourali Fashtomi and Mohseni, 2006); on effective stocking density of eggs and larvae in incubators and rearing tanks (Mohseni et al., 2000); 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); 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); sperm has been cryo-preserved to conserve the gene pool (Vecsei and Artyukhin, 2001); sperm studies evaluating ionic composition and osmolality of seminal plasma, sperm density and motility in regard to sperm cryopreservation (Alavi et al., 2006), sperm density and fertilisation rate (Nazari et al., 2005), and on sperm motility (Hadi Alavi et al., 2004); induction of ovulation using glycerin as a solvent for hypophysis powder proved better than physiologic serum (Noroozi et al., 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); the maximum allowable concentration of Safid River sediments as determined in aquaria was 1536.74 mg/l (Yosefi Garakoei et al., 2006); Feyzbakhsh et al. (2006) found the micro-cesarean method of extracting eggs from brood stock was better than conventional methods; 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, Jafari Shamushaki et al. (2008) on amino acids in food pellets increasing consumption, 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 and Shariat, 2006).

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). Acipenser primigenius Chalikov, 1944 is a hybrid of this species and Acipenser gueldenstaedtii (Eschmeyer et al., 1996). The Farsi name is استرلياد (esterliad).

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). Shabani et al. (2003; 2006) found no significant differences between Volga River and Gorgan, Tajan and Safid River fish of Iran when examining mtDNA.

A hybrid with Acipenser nudiventris is reported from the Safid River (Nedoshivin and Il'in, 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).

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 2.2 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 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 L∞ = 219 cm and K = 0.06 year^-1 (www.shilat.com, downloaded 28 February 2007).

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, Cobitis taenia, 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.

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. 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.

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 and biochemistry. 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; 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.

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).

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. 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