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Acipenser ruthenus:   (click for more)

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  • Acipenser pygmaeus  Pallas, 1814:102.
  • Acipenser marsigli  Brandt, 1833:352.
  • Acipenser gmelini  Fitzinger and Haekel, 1836:276.
  • Acipenser primigenius  Chalikov, 1944:47.
  • Acipenser ruzskyi  Ioganzen, 1946:173.
  • Acipenser ruthenus brevirostris  Antipa, 1909:250.
  • Acipenser ruthenus obtusirostris  Brusina, 1902
    FAO Names
    En - Sterlet sturgeon, Fr - Sterlet, Sp - Esterlete.
    3Alpha Code: APR     Taxonomic Code: 1170100104
    Scientific Name with Original Description
    Acipenser ruthenus  Linnaeus, 1758. Syst. Nat., ed X: 237 Russia.
    Diagnostic Features
    Snout and caudal peduncle subconical. Snout length and form highly variable. Generally, sterlets with pointed snouts tend to be young specimens, and the average age of those with blunt snouts is greater.  Spiracle present. Gill membranes joined to isthmus. Mouth transverse and lower lip with a split in the middle. Barbels fimbriate.  11-27 gill rakers.  D:32-54, A:16-34.  11-18 dorsal scutes. 56-71 lateral scutes. 10-20 ventral scutes.  Numerous bony plates between the rows of scutes.  Colouration varies greatly. Back usually dark greyish-brown. Belly yellowish white. The scutes are dirty white and the fins, grey. 
    Geographical Distribution

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    The sterlet is a Eurasian species inhabiting rivers flowing into the Caspian, Black, Azov, Baltic, White, Barents, and Kara Seas (Sokolov & Vasilev, 1989).
    Habitat and Biology
    The sterlet is a potamal freshwater fish that seldom occur in large lakes. It inhabits the lowland and foothill zones of the rivers and usually stays in the current in deep depression in the riverbed. Small specimens are often encountered in sandy shallows. The two kinds of spawning sites are the river bed at a depth from 7 to 15 m, and floodplain sites flooded by the rising spring water, on pebbles and rarely on gravelly-sand bottoms.It generally behaves as a resident fish.Does not undertake long migrations.Their main food in all rivers is benthic organisms, mainly insect larvae ( Trichoptera, Chironomidae, Ephemeroptera, Plecoptera, and Simuliidae ); small mollouscs (Sphaeridium spp., Pisidium spp. and Viviparus), annelids, other invertebrates , and also fish eggs, including those of other acipenserids, are also included in their diet. Young specimens feeds mainly on trichopteran and chironomid larvae. In the Volga river near its mouth, gammarids account for over 90 % of the food by weigh in young specimens. With increasing size, the role of tricopterans increases while that of chironomidae decreases.
    Males reach sexual maturity at an age of 3-6 years old, one to two years earlier than the females. The spawning periodicity remains open: spawn every year or only after a pause (shorter for males than for females) of one or more years?. Possibly, in the northern part of the range, the onset of sexual maturity would be later, and a considerable proportion of the adult specimens would not reproduce during every spawning season (Sokolov & Vasilev, 1989). During the spring floods they do swim upstream in the river for spawning. Males appear at the spawning ground before females at the water temperature from 9 to 11 ºC. Females reach the spawning ground later, at a water temperature from 12 to 13 ºC.  The optimal water temperature for the reproduction of sterlets ranges from 12 to 17 ºC.  The sterlet has the shortest life span (22-24 years old) in the genus Acipenser and females live longer than males.
    Maximum size 125 cm and a weight of 16 kg; usually below 100 cm and 6 to 6,5 kg.
    Interest to Fisheries
    The sterlet is a very important commercial fish. They were caught with nets, fish traps, willow baskets, and with barbed lances. At the present time, most of the sterlets captured come from the Danube River system.
    They are usually marketed alive, and rarely refrigerated, frozen or smoked. Males of this species are used to produce the bester, the first generation hybrid with beluga (Huso huso) females. The sterlet is an important fish in aquaculture, reahing sexual maturity in containers filled with warmed water (Sokolov & Vasilev, 1989 ).
    Local Names
    AUSTRIA : Sterlett .
    BULGARIA : Chiga .
    DENMARK : Sterlet .
    FINLAND : Sterletti .
    FRANCE : Sterlet .
    GERMANY : Sterlet .
    HUNGARY : Kecsege .
    NORWAY : Sterlett .
    POLAND : Sterlet a. czeczuga .
    ROMANIA : Cega .
    RUSSIAN FED. : Sterlyad' .
    SPAIN : Esterlete .
    SWEDEN : Sterlett .
    UKRAINE : Sterljad .
    UNITED KINGDOM : Sterlet .
    USA : Sterlet .
    There are more synonyms that listed up. Birstein & Bemis (1997) consider that all intraspecies, forms and subespecies of A.ruthenusdescribed by different authors (see Berg, 1948 and Sokolov & Vasilev, 1989) are invalid until detailed molecular and morphological studies of different forms within these species can be performed.
    Banarecu, P - 1964. Pisces-Osteichthyes Fauna Republicii Populare Romine. 13. .  Ed: Academiei Republicii Populare Romine, Bucaresti.
    Berg, L.S - 1962. Freshwater fishes of the U.S.S.R. and adjacent countries. Israel Program for Scientific Translations Ltd, Jerusalem. Volume 1, 4th edition. .  Russian version published 1948
    Birstein, V.B. & W.E. Bemis - 1997. How many species are there within the genus Acipenser? Environ. Biol. Fish. .  48: 157-163..
    Birstein, V.J. - 1993. Sturgeons and paddlefishes: threatened fishes in need of conservation. Conserv. Biol. .  7:773-787..
    Birstein, V.J., Bemis, W.E & J.R. Waldman - 1997. The threatened status of acipenseriform species: a summary. Environm. Biol. Fish. .  48:427-435..
    Hensel, K. & J. Holcík - 1997. Past and current status of sturgeons in the upper and middle Danube River. Environ. Biol. Fish. .  48:185-200..
    Reshetnikov, Y.S, N.G. Bogutskaya, E.D. Vasil'eva, E.A. Dorofeeva, A.M. Naseka, O.A. Popova, K.A. Savvaitova, V.G. Sideleva & L.I. Sokolov - 1997. An annotated check-list of the freshwater fishes of Russia. J. Ichthyol. .  37(9): 687-736..
    Rochard, E., Castelnaud, G. & M. Lepage - 1990. Sturgeons (Pisces:Acipenseridae); threats and prospects. J. Fish Biol. .  37 (A): 123-132..
    Sokolov, L.I & V.P. Vasilev - 1989. Acipenser ruthenus Linnaeus, 1758. In J. Holcíck (ed.) The freshwater fishes of Europe, Vol. I, Part. II: General introduction to fishes, Acipenseriformes. .  p: 227-263.. Aula-Verlag.
    Svetovidov, A.N. - 1964. Handbook of the fauna of the USSR, fishes of the Black Sea. Izdatel'stvo Nauka .  550 p.. Moscow
    Vasilev, V.P. - 1980. Chromosome numbers in fish-like vertebrates and fish. J. Ichthyol. .  20(3):1-38..
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