Species Accounts - Cyprinidae - Abramis
Genus Abramis
Cuvier, 1816
The bream genus comprises 4 species found in Europe, Asia Minor and the Caspian and Aral Sea basins. There are 2 species in Iran but see also Blicca and Vimba.
The genus is characterised by a strongly compressed and deep body, a scaleless keel between the vent and pelvic fins, a scaleless groove on the back in front of the dorsal fin but not behind the fin, pharyngeal teeth in 1 row, compressed and with a groove on the grinding surface, dorsal fin short and spineless, anal fin long to very long, and lateral line decurved.
Durand et al. (2002) studying cytochrome b data concluded that this genus is not monophyletic since A. ballerus and A. sapa are placed basal to a group of species including A. brama, Blicca bjoerkna, Vimba species, Acanthalburnus microlepis and Acanthobrama.
.Abramis brama
(Linnaeus, 1758)
Common names
سيم (sim or seam = silver), ماهي سيم (= mahi-ye sim, meaning silver fish).
[capag, chakag, chapakh or chipakh, all in Azerbaijan; gundogar tarany (topi) in Turkmenian; vostochnyi leshch or Oriental bream in Russian; common, bronze, eastern or carp bream].
Systematics
Cyprinus Brama was originally described from Sweden.
Abramis brama orientalis Berg, 1949 is reported for the Caspian and Aral Sea basins but Koshara and Izyumov (1991) restricted this subspecies to the Aral Sea with the type subspecies in the Caspian Sea basin. They did not examine any Iranian material. Kozhara and Mironovskiy (1988) using numbers of pores in the seismosensory canals for samples taken over a wide range of this species identified 8 population groups but did not recognise subspecies. Some earlier works also indicate that no subspecies exist (see Reshetnikov et al., 1997).
Caspian material reportedly has more gill rakers, fewer vertebrae and fewer scales than the type subspecies from the Baltic Sea basin (Berg, 1948-1949) but further study over the whole range of the species is needed to clarify the situation, analyzing for clines. The Iranian populations are referred to the type subspecies for the moment. The type locality of this subspecies is the Aral Sea at Muinak and Lake Yaskhan in the Uzboi.
Khar and Keyvan (2007) compared fish from the Anzali wetland and the Caspian Sea, both meristically and morphometrically. Significant differences were noted in particular for morphometric characters and were attributed to differing habitats.
Abramis brama bergi Grib and Vernidub, 1935 (preoccupied by Abramis sapa bergi Belyaeff, 1930 according to Eschmeyer et al. (1996)) was originally described from the Aral Sea at Muinak and is also found in the Uzboi Valley of Turkmenistan, north of the Iranian border (Berg, 1948-1949). It was replaced by Abramis brama orientalis.
A syntype of Cyprinus brama is in the Natural History Museum, London as a skin under BM(NH) 1853.11.12:147 (Eschmeyer et al., 1996).
Artificial hybrids with Rutilus frisii kutum and Rutilus rutilus have been bred in Iran (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 39-40, 1996).
Key characters
The scaleless keel on the belly, deep body, high number of branched rays in the anal fin (22-30), modally 9 branched dorsal fin rays, and uniserial pharyngeal teeth are key characters.
Morphology
The mouth is small but highly protrusible. There is a strong dorsal ridge anterior to the dorsal fin. Dorsal fin with 3 unbranched and 8-10, usually 9, branched rays, anal fin with 3 unbranched and 22-30 branched rays. Lateral line scales 48-60. The lateral line is moderately decurved. Scales are regularly arranged, sheathing the anal fin base. Scales have numerous fine circuli but only relatively few posterior and even fewer anterior radii. In a fish about 6 cm long there are as few as 8 total radii. The focus is almost central and the anterior scale margin is wavy. There is a pelvic axillary scale. The ventral keel between the pelvic fin bases and the anal fin is well-developed. Gill rakers number 18-30 and are short, reaching the raker below when appressed. They are strongly tuberculate on the inner surface. Vertebrae 38-47, usually 42-44 in the Caspian populations (lower counts in literature may not include 4 Weberian vertebrae). The chromosome number is 2n=50-52 (Klinkhardt et al., 1995). The chromosome number based on fish from the Iranian coast of the Caspian Sea is 2n = 50 with the number of arms NF = 82 and the karyotype being 8 pairs of metacentric, 8 pairs of submetacentric and 9 pairs of acrocentric chromosomes (Nahavandi et al., 2001).
Pharyngeal tooth formula modally 5-5, with variants of 6-5 (2.2-4.8%), 5-4 (2.2-4.4%) and 4-5 (8.6%) for collections from the Caspian and Aral seas basins in former Soviet waters (Vasil'yeva and Ustarbekov, 1991). Other variants are summarised in Tadajewska (1998). Teeth bear a small hook at the tip in the main row and have long, narrow and flat crowns. In young fish, the hook is more pronounced and the crown has a few tubercles or a series of serrations. The gut is s-shaped with a small anterior loop.
Khar et al. (2007) compared this species from the Caspian Sea and the Anzali wetland and found significant morphometric, but not meristic, differences, attributing this to habitat conditions.
Meristic values for Iranian specimens are:- dorsal fin branched rays 9(12) or 10(1); anal fin branched rays 24(3), 25(3), 26(1), 27(4) or 28(2); pectoral fin branched rays 16(7) or 17(6); pelvic fin branched rays 8(13); lateral line scales 49(2), 50(2), 51(3), 52(3), 54(1) or 55(2); total gill rakers 23(3), 24(2), 25(6), 26(1), or 27(1); total vertebrae 44(12) or 45(1); and pharyngeal teeth 5-5(12).
Sexual dimorphism
Males bear tubercles on the head, body and fins. Scale tubercles appear singly, in pairs or occasionally as 3 per scale. There is some evidence of differences in gill raker counts between the sexes but sometimes the males have higher mean counts and sometimes the females. Abdurakhmanov (1962) reports eye diameter, greatest body depth and predorsal distance to be greater in females and dorsal fin base length, pectoral and pelvic fin lengths and interorbital width to be greater in males from Azerbaijan.
Colour
In Dagestan, the resident form is darker in colour than the semi-anadromous form (Shikhshabekov, 1969). Overall colour is silvery. The iris is silvery with a little grey pigment on the upper part. The dorsal and caudal fins are pale grey, almost transparent, to a greyish-blue, the pectoral fins may be grey or colourless, and pelvic fins are colourless. All fins except the pectorals have black tips. Large fish are a dark olive-green on the back and bronze on the flanks and old fish may have all fins black. The peritoneum is silvery to light brown in preserved fish.
Size
Attains 82.0 cm total length and 11.55 kg.
Distribution
Found from the British Isles across Europe north of the Pyrenees and Alps eastwards to the Black, Caspian and Aral sea basins although not in western Transcaucasia. In Iran it is found from the Astara to the Atrak rivers in the whole Caspian Sea basin (Kozhin, 1957) including the Anzali Mordab, its outlets and tributaries and the Siah-Keshim Protected Region (Holčík and Oláh, 1992; Riazi, 1996; Kiabi et al., 1999), the Safid River (Abbasi et al., 1999), Gorgan Bay (Derzhavin, 1934), and freshened areas of the Caspian Sea.
This species is also recorded from the Karakum Canal and Kopetdag Reservoir in Turkmenistan (Shakirova and Sukhanova, 1994; Sal'nikov, 1995) and may eventually reach Iranian waters in the Tedzhen (= Hari) River basin where it has been reported by Aliev et al. (1988).
Zoogeography
This species is part of a northern European and northern Southwest Asian fauna whose zoogeographical history has not been researched. It origins may lie in a Danubian or Sarmatian fauna.
Habitat
The bream prefers still water and is low in numbers even in rivers with weak current. Abundant littoral vegetation and a very muddy bottom are favoured in lakes for reproduction and feeding respectively. It retreats to deeper water in winter, forming schools numbering in the many thousands, packed densely together (Muus and Dahlstrøm, 1999). It is more numerous in the Anzali Mordab along the Caspian coast of Iran (Jolodar and Abdoli, 2004).
This species can tolerate high temperatures of 33-34°C in southern areas like Iran for a time but above 28°C growth rate decreases. Adults can live in a salinity of 12.9‰, perhaps 14‰, and eggs may be fertilised at a salinity of 10.2‰. However preferred levels are 2-4‰. Salinity and water level changes have significant effects on abundance in this species. Population densities vary markedly in both fresh and brackish water populations.
Bream living in the Caspian Sea basin are semi-migratory. They feed in the brackish sea but spawn and winter in the lower reaches and deltas of large rivers. A spring migration up rivers begins with ice melt or warmer temperatures in the sea and after spawning the fish return to disperse and feed in the sea. In the fall the fish migrate into the deeper parts of river deltas. In Russian parts of the Caspian they are found at depths not exceeding 4-5 m but Knipovich (1921) reports them at 14.6-16.5 m, possibly deeper, in the Iranian Caspian Sea.
There were spring and winter migrants in the southwestern Caspian including the Anzali Mordab (A. M. Shukolyukov in Berg, 1948-1949). The spring bream had a longer snout, deeper head, lower body, lower dorsal and anal fins, and more scales. The spring bream entered the Mordab for spawning only while the winter bream overwintered in bottom pools. Changing conditions in the mordab environment in the late 1980s and the 1990s may have altered this migration. Riazi (1996) reports that this species migrates into the Siah-Keshim Protected Region of the Anzali Mordab.
Age and growth
The resident form in Dagestan is slightly inferior in length (2-3 cm), weight and age to the semi-anadromous form (Shikhshabekov, 1969). In Dagestan, the resident form becomes sexually mature at 3 years for females and 2 years for males at lengths of 23-26 cm and weights of 200-240 g while the semi-anadromous form matures at 4 years and a length of at least 25-28 cm and a weight of 250-300 g. In Uzbekistan females mature at lengths ranging from 10.5 to 27 cm in different reservoirs, usually at age 3 (Kamilov, 1994). Maturity is attained at a younger age in southern waters generally in this species and this probably applies in Iran. The maturity range is 2-10 years with males often maturing a year earlier than females. Females predominate in the older age groups.
Maximum age exceeds 32 years although in southern waters the maximum age does not exceed 15 years. Semi-migratory bream of the Caspian Sea have a fast growth rate and a short life cycle, reaching 37.5 cm standard length by age 8.
Most fish examined by Razivi et al. (1972) from commercial catches in Iran were 3-6 years old, 25.6-39.8 cm long and weighed 249-950 g. Over a three year period there was a decline in average age. Young and immature fish formed most of the catch in 1998-1999 when one-year-old fish comprised 20.3% and two-year-old fish 37.3%. The average length, weight and age for 1998-1999 were 22.5 cm, 212.2 g and 2.4 years. The rate of recruitment was 4.6% in 1991 and 2.7% in 1992 (Saiad Borani, 2001). Abdolmalaki (2006b) studied Caspian Sea fish from Iran and found mean fork length, weight and age to be 21.7 cm, 181 g and 2.72 years, respectively. The length-weight relationship was W = 0.2312L2.9 and von Bertalanffy growth parameters were Lt = 45[1-exp-0.125(t 2.768)], and the instantaneous rate ot total (Z), natural (M) and fishing mortality (F) were 0.92 year-1, 0.28 year-1 and 0.64 year-1, respectively. The exploitation rate (E) was 0.7. Biomass was calculated as 46.362 t and the maximum sustainable yield was 14.99 t.
Food
Young fish feed on zooplankton. Adults use a strong sucking power and a tube-like snout to feed on invertebrates and detritus in mud. This sucking action leaves evident "bream pits" in soft mud, depressions about 10 cm across. In the northern Caspian Sea food items include Cumacea, Corophiidae, the clams Adacna (69% by weight) and Monodacna, Tendipedidae (= Chironomidae), Polychaeta, Gammaridae, Mysidae, and Oligochaeta. When overcrowded or in turbid conditions, plankton may be eaten in addition to the normal foods (Muus and Dahlstrøm, 1999). Large specimens may feed on small fishes. A specimen from the Langarud, Gilan, 158.6 mm standard length, contained chironomids.
Reproduction
Bream enter the Kura River from December to February with a peak in January (Berg, 1959) and travel some distance upriver. These fish have an average length of 31.1 cm and an average weight of 633 g. Length and weight in Azerbaijan vary from 25.4 to 31.9 cm and 306 to 681 g. Bream enter the Anzali Mordab, the main spawning area in the southern Caspian, in the first half of March until the beginning of May. Males precede females on the spawning ground by about 3 days and males outnumber females by about 3 to 1. Spawning begins in the first half of April in shallow water and lasts until mid-May. Fecundity in Dagestan reservoirs reaches 191,000 eggs (Shikhshabekov, 1969), in Uzbekistan reservoirs 772,000 eggs (Kamilov, 1994) and a maximum elsewhere of 941,000 yellowish eggs is reported. Bream spawn repeatedly with different partners and although most bream spawn only once a year, multiple spawnings are known. Spawning occurs in masses over a period of 2-3 days triggered by temperatures of 12-13°C or above. The commonest spawning temperature for the species overall is 16-18°C. Spawning is most intensive at night in some populations while others show late morning and late afternoon peaks. There is much splashing of the water by their tails and the noise can be heard some distance away although the fish are easily scared into deeper water by any noise like human voices. Males probably defend territories, attracting females and scaring other males away. There can be up to 2.3 million eggs per sq m however, suggesting that many fish may spawn in the same area. Eggs are deposited in quiet water, most commonly at depths of 20-80 cm, and they adhere to aquatic plants or flooded land plants. Eggs are up to 1.9 mm in diameter.
Parasites and predators
Jalali and Molnár (1990a) record the monogenean Dactylogyrus zandti from this species in the Safid River. Sattari and Faramarzi (1997) record Caryophyllaeus fimbriceps from 28% of bream in the Anzali lagoon. Naem et al. (2002) found the following parasites on the gills of this species from the western branch of the Safid River, namely the monogenean trematodes Dactylogyrus zandti and D. wonderi. Masoumian et al. (2005) report the protozoan parasites Ichthyophthirius multifilis and Trichodina perforatafrom this species in the Aras Dam in West Azarbayjan. Jalali et al. (2005) summarise the occurrence of Gyrodactylus species in Iran and record G. elegans from fish in the Safid River. Sattari et al. (2005) survey this species in the Anzali wetland, recording Raphidascaris acus larvae. Pazooki et al. (2007) record various parasites from localities in West Azarbayjan Province, namely Ligula intestinalis, Digrama sp., Argulus foliaceus and Caryophyllaeus laticeps. Sattari et al. (2007) record the cestode Caryophyllaeus fimbriceps, the digenean Diplostomum spathaceum and the monogeneans Dactylogyrus extensus and Gyrodactylus sp. in this species in the Anzali wetland of the Caspian shore and also mention that the monogenean Diplozoon sp. is also known from this species in the Iranian Caspian Sea.
The Caspian seal, Pusa caspica, is a predator on this species (Krylov, 1984). Various predatory fishes take bream including Huso huso, Perca fluviatilis, Sander lucioperca, Aspius aspius and Silurus glanis but this is comparatively rare especially when bream exceed 20 cm in length. Birds such as grebes, herons, divers and cormorants are also predators.
Economic importance
This species is an important food fish being both tasty and of large size. In addition it can live out of water for some time and thus remain fresh while being transported to market.
Nevraev (1929) gives catches for various fishing regions in Iran in the early twentieth century. For the Anzali region from 1901-1902 to 1913-1914 the catch was 2283 to 419,117 individuals, for the Safid River region from 1908-1909 to 1917-1918 the catch was 17,195 to 474,200 individuals (rising steadily but falling in 1917-1918) with no fish reported in the years 1899-1900 to 1907-1908 and in 1918-1919, and in Astrabad (= Gorgan) region from 1900-1901 to 1912-1913 the catch was 20,600 to 1,381,500 individuals with no clear trend, the catches varying markedly from year to year. The commercial catch in Iran from 1956/1957 to 1961/1962 varied from 0 to 158 kg (Vladykov, 1964), from 1965/66 to 1968/69 varied from 0 to 29 tonnes (Andersskog, 1970) and from 1963 to 1967 from 0.5 to 16.0 tonnes (with no reported catch in the first 3 years)(RaLonde and Walczak, 1970b). The catch in the Bandar-e Anzali region from 1933/34 to 1961/62 varied between only 2 kg and over 1394 t with some years reporting no catches. Holčík and Oláh (1992) report a catch of 34 kg in the Anzali Mordab for 1990 and for the period 1932-1964 catches ranged from none to 1133.5 tonnes annually. The total catch of the Northern Shilot (Fisheries Company) from 1965/66 to 1968/69 varied between 13 and 74 t (RaLonde and Walczak, 1972). There are obviously wide variations in annual catches and/or in reporting statistics. The general trend is one of decline in catches with large fish being caught and the average stock size being lowered, resulting in a decreased spawning success. This species has a deep body and immature fish are easily caught. The catch in the Anzali Mordab was important until the end of the 1940s but had virtually disappeared by the 1980s (Petr, 1987). Abdolmalaki (2006b) gives a total catch of 17 t for the 2000-2001 fishing season, only 0.1% of the commercial catch in Iranian coastal waters of the Caspian Sea. In contrast, the total catch for Iranian waters was estimated at 26.3 tons of which 15.4 tons was from beach seines; most fish were immature and undersized (Abdolmalaki, 2006a).
In former Soviet waters of the Caspian Sea, the age composition in commercial catches was 2-10 years, with the great majority being 3-5 years old. Trawls, seines, pound nets and gill nets are used in the northern Caspian Sea to catch the bream with 60-70% being taken in spring. Spawning and breeding farms were established in the former Soviet Union to rear young fish. Catches in the Volga-Caspian and Ural regions has been as high as 344,900 centners, prior to 1930, and in the Aral Sea in 1931 the catch was 115,200 centners.
Mono- and poly-culture of this species has been carried out in Iran (Annual Bulletin 1993-94, Iranian Fisheries Research and Training Organization, Tehran, p. 77-78, 1995). Polyculture comprised 70% Abramis brama, 20% silver carp (Hypophthalmichthys molitrix) and 10% grass carp (Ctenopharyngodon idella) and gave a greater yield than monoculture. From an average initial weight of 30 g, fish attained averages of 188 or 211 g in monoculture (average 200 g) and 221 or 278 g (average 250 g) in polyculture with maximum weights of 300 or 580 g at the end of two one-year periods. Water temperatures were 9-33°C (Annual Report, 1994-1995, Iranian Fisheries Research and Training Organization, Tehran, p. 38-39, 1996; Danesh-e-Khoshashi, 1997).
A state supported stocking programme has released about 70-80 million fingerlings into the Anzali Mordab, all descended from a single pair mating 8 years ago (Rana and Bartley, 1998a; 1998b). These fish are intolerant of low oxygen and so perform poorly under pond conditions. Stocks may be imported from Azerbaijan in the future (Rana and Bartley, 1998b). The release of 70.46 million fry in 1992-1993 to 1998-1999 period has not been successful in restoring the stocks in Iran. Stock depletion was attributed to improper fishing methods, pollution, destruction of spawning grounds, presence of predatory Esox lucius and Silurus glanis in fry stocking areas, and lack of necessary arrangements in regard to artificial spawning (Saiad Borani, 2001).
The roe or eggs of this species have been implicated in poisoning (Halstead, 1967-1970; Coad, 1979b) and should be avoided (see under the genus Schizothorax for more information on egg poisoning). Fish should be carefully cleaned in the spawning season to remove the eggs and ensure against contamination of flesh. Severe cases of egg poisoning in other species have resulted in death.
This species has been used in Iran for experimental studies, e.g. on the toxicity and LC50 of phenol and 1-naphthol (Shariati et al., 2004).
Robins et al. (1991) list this species as important to North Americans. Importance is based on its use as food and in aquaculture.
Conservation
The subspecies has been proposed for inclusion in the "Red Book of the U.S.S.R." which forms the basis for measures to protect species (Pavlov et al., 1985).
RaLonde and Walczak (1970b) reported that 90% of the bream caught in Iran in 1970 were immature and the stock was in danger of extinction. About 19-20% of commercial catches in the Volga region are from hatchery raised stock (Petr, 1987) and it was thought that stocking could help this species in Iran. During the 1980s and 1990s there were practically no catch figures for this species in Iran. Artificial propagation began in 1986 on an experimental basis and 6 million fish were released (Ghenaat Parast, 1993). In 1992-1993 (an Iranian calendar year), 2.4 million fingerlings were released into the Anzali Mordab and nearby rivers, a 100% increase over the previous year (Abzeeyan, Tehran, 4(2):VI, 1993). Total production in government hatcheries for 1990 was 0.66 million fingerlings, in 1991 2.28 million and in 1992 5.3 million fingerlings (Emadi, 1993a). Fingerling production was 11.217 million in 1995 and 8.5 million in 1996 (Bartley and Rana, 1998a; 1998b). In 1999-2000, 20 million juveniles were released (Iranian Fisheries Research Organization Newsletter Newsletter, 23:4, 2000). From October to March 2000, 14 million juveniles raised in the Shahid Ansari aquaculture and breeding centre in Gilan were released into the Caspian Sea and neighbouring water bodies (Iranian Fisheries Research Organization Newsletter, 26:2, 2001). Illegal fishing and non-standard nets threaten the stocks (Annual Report, 1995-1996, Iranian Fisheries Research and Training Organization, Tehran, p. 19-20, 1997). Billard and Cosson (2002) give an annual production of 15 million alevins.
Ramin (1997) details studies on the artificial breeding of this species in Iran, based on 38 brooders, with the goal of saving it from extinction. Gonadotropic hormone extracted from the pituitary of the common carp was used to induce brooders. One or two doses at 5-6 mg/kg body weight gave optimum stripping of eggs at 18°C. Fertilisation rate was 75-95% and hatching rate was 75-85%. Incubation took nearly 4 days at 18-21°C. The grey, pink or yellow eggs numbered 9142-60,050 per spawner with a swelled diameter of 1.0-1.2 mm. The yolk sac was absorbed after 72 hours and newly hatched larvae were 2.9-3.7 mm long.
Kiabi et al. (1999) consider this species to be vulnerable in the south Caspian Sea basin according to IUCN criteria. Criteria include commercial fishing, sport fishing, few in number, habitat destruction, limited range (less than 25% of water bodies), not present in other water bodies in Iran, and present outside the Caspian sea basin. Nezami et al. (2000) consider this species to be endangered because of overfishing, habitat destruction and spawning groundn degradation.
Further work
Stocks should be carefully monitored on a continuing basis and efforts made to resurrect this commercial species.
Sources
The chief literature summary for earlier works is Backiel and Zawisza (1968) although little apparently refers to the Caspian basin populations and even less to those of the Iranian shore. Nevertheless this work gives a general overview of biology and general comments above are based on it.
Iranian material: CMNFI 1970-0542, 4, 75.4-173.7 mm standard length, Gilan, Old Safid River estuary (37°23'N, 50°11'E); CMNFI 1970-0543A, 1, 70.0 mm standard length, Gilan, Caspian Sea at Hasan Kiadeh (37°24'N, 49°58'E); CMNFI 1971-0343, 1, 158.6 mm standard length, Gilan, Langarud at Chamkhaleh (37°13'N, 50°16'E); CMNFI 1980-0127, 3, 166.1-170.1 mm standard length, Gilan, Caspian Sea near Hasan Kiadeh (37°24'N, 49°58'E); CMNFI 1980-0142, 1, 160.6 mm standard length, Gilan, Nahang Roga River (no other locality data); CMNFI 1980-0906, 3, 105.6-176.0 mm standard length, Gilan, Caspian Sea basin (no other locality data).
Abramis sapa
(Pallas, 1814)
Common names
سابا, سبا (saba, from the species name), سيم (sim = silver), ماهي سيم كند پوزه (= mahi sim kondpuzeh, meaning bluntsnout silver fish).
[pori or poru, both in Azerbaijan; tarashka, taran' and rybets, erroneously in Azerbaijan; yuzhnokaspiiskaya beloglazka or South Caspian white-eye bream in Russian; white-eye bream, southern white-eye bream, Danube bream].
Systematics
Cyprinus Sapa was originally described from the Sura, Samara and Kinel' rivers in the Volga River basin. No types known.
May be placed in the genus Ballerus Heckel, 1843 (see Hensel (1978), Shcherbukha (1973), Howes (1981), Bogutskaya (1986) and Bogutskaya and Naseka (2004) for various opinions). The nominate subspecies was described from the Volga River and tributaries.
The subspecies reported from the southern Caspian Sea basin is Abramis sapa bergi Belyaev, 1929, described from the Kura River in Azerbaijan. Eschmeyer et al. (1996) date this subspecies to 1930 although the article is dated 1929. Recognition of subspecies is disputable (Reshetnikov et al., 1997).
Key characters
The scaleless keel on the belly, deep body, very high number of branched rays in the anal fin (31-44), modally 8 branched dorsal fin rays, and uniserial pharyngeal teeth are key characters.
Morphology
Dorsal fin with 2-3, usually 3, unbranched and 7-9, usually 8, branched rays, anal fin with 3 unbranched and 31-44, mostly 34-38 branched rays, pectoral fin branched rays about 15 and pelvic fin branched rays about 8. Lateral line scales 42-55, mostly 51-52, regularly arranged over the body. Scales bear numerous very fine circuli, an almost central focus, numerous to few posterior radii (quite variable between scales of similar size) and few to none anterior radii. The anterior scale margin is wavy. A pelvic axillary scale is present. There is an evident, scaleless keel on the belly between the pelvic fin bases and the anal fin. Gill rakers 18-25, short, reaching the raker below or almost the second raker when appressed. Vertebrae 45-48. Pharyngeal teeth 5-5, with elongate, narrow and flattened, concave or rounded crowns below a hooked tip. The gut is s-shaped with a small anterior loop. The chromosome number is 2n=50 (Klinkhardt et al., 1995).
Belyaev (1929) for Kura River fish gives lateral line scale counts as 48(3), 49(6), 50(24), 51(50), 52(54), 53(16) or 54(7) and anal fin branched rays as 32(1), 33(5), 34(22), 35(32), 36(38), 37(47), 38(25), 39(9), 40(5), 41(2) or 42(1). This subspecies is distinguished from the type form in the Black Sea (Don River) by fewer lateral line scales and anal fin branched rays, a longer snout, smaller eyes, less deep body, lower dorsal fin, shorter anal fin, and longer postorbital length.
Sexual dimorphism
Unknown.
Colour
The Caspian subspecies has a dark back with a bluish tint, flanks and belly are silvery, fins are a greyish-white and sometimes have a black margin, and the iris is silvery. The peritoneum is dark brown in preserved fish.
Size
Attains 41 cm and 0.8 kg.
Distribution
Found in the basins of the Black, Caspian and Aral seas. Reported from the gut of a Silurus glanis in the Anzali Mordab (Derzhavin, 1934) but not found in recent years (Holčík and Oláh, 1992). Other reports are from the lower Safid River at Hasan Kiadeh (Belyaev, 1929; Derzhavin, 1934) and in the Aras River at Karadonly (Berg, 1948-1949).
Zoogeography
This species is part of a northern European and northern Southwest Asian fauna whose zoogeographical history has not been researched.
Habitat
This species feeds in brackish water but spawns and overwinters in the lower reaches of rivers. It is commonest along the western shore of the middle and southern Caspian Sea.
Age and growth
Females are 28-29 cm long on average, maximum 39 cm, while males are about 24 cm, maximum 30 cm (Belyaev, 1929). Males and females mature at 2-3 years and life span is 5 years in Azerbaijan (Abdurakhmanov, 1962).
Food
Food items include small molluscs, crustaceans and insect larvae as well as some plant fragments and detritus. Young feed on zooplankton.
Reproduction
A migration into rivers, particularly the Kura, occurs in winter when temperatures fluctuate from 5 to 10°C (Belyaev, 1929). The run begins in November and peaks in January. The Kura migration was once over 700 km from the mouth. Spawning occurs in rivers with gravel bottoms or dense vegetation from April to May. Fecundity reaches about 150,000 eggs with diameters up to 1.8 mm. Eggs adhere to stones or plants.
Parasites and predators
Eaten by Silurus glanis (Derzhavin, 1934).
Economic importance
Up to 1-2 million fish were caught in the Kura at spawning (Belyaev, 1929). The annual average catch in Azerbaijan in 1931-1935 was 1,860,000 fish weighing 6200 centners.
Conservation
The subspecies A. sapa bergi has been proposed for inclusion in the "Red Book of the U.S.S.R." which forms the basis for measures to protect species (Pavlov et al., 1985). It has always been very rare in Iran and its absence from the Anzali Mordab may be due to loss of spawning grounds (Holčík and Oláh, 1992). Lelek (1987) considers this species to be rare to vulnerable in Europe.
Further work
The status of this species in Iran should be assessed by field surveys. It is apparently quite rare and was not caught during two collecting trips along the Caspian shore in the 1970s. It is recorded only from two localities in Iran in 1929 and 1934.
Sources
Iranian material:- None available, based on literature reports.
Comparative material:- CMNFI 1986-0458, 2, 209.0-211.7 mm standard length, Germany, Danube River (48º58'N, 12º18'E); BC 59-301, 2, 136.3-154.2 mm standard length, Ukraine, Tisa, Danube drainage (no other locality data).
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