Species Accounts - Acipenseridae

Revised:  19 June 2008

There is an extensive literature on sturgeons, particularly those in the Caspian Sea. Accordingly accounts are split by genus and a separate file (Caviar) treats that famous delicacy.

The family is found in Europe, northern Asia and North America with 4 genera and 25 species. 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. 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 and 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 (2006), Karayev (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 trutta, Barbus 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

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).

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; Koochekian 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:-
 

	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%.

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. 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.

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

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© Brian W. Coad (www.briancoad.com)