Russian sturgeon (Acipenser gueldenstaedtii)
|Size||Length: 2.2 - 2.4 m (2)|
|Weight||65 - 115 kg (2)|
The Russian sturgeon is classified as Critically Endangered (CR) on the IUCN Red List (1) and listed on Appendix II of CITES (3).
The Russian sturgeon (Acipenser gueldenstaedtii) belongs to an ancient and unique group of bony fish (1) (4), relics from the time of the dinosaurs, which still swim the waters of the northern hemisphere today. A prehistoric giant, the Russian sturgeon can reach lengths of nearly two and a half metres (2), which is longer than the average human.
The Russian sturgeon’s mouth is located on the underside of its narrow, pointed head, and is preceded by four whisker-like barbels, which it uses, along with its sense of smell, to detect prey on the seabed or the bottom of the river (5).
Its elongated body is typically a dark olive colour, although some individuals appear almost black. The Russian sturgeon also possesses rows of bony plates which remain prominent throughout life and range from white to yellowish gold, in contrast to its dark body (6).
The Russian sturgeon is native to the Black, Azov, and Caspian Seas in eastern Europe and the Middle East, as well as the major river systems throughout this region. Today, it is confined to the lower parts of these rivers and the seas they run into (1).
The Russian sturgeon inhabits shallow coastal areas at sea, and deep sections of large, fast-flowing rivers (1).
The Russian sturgeon matures slowly; males typically do not reproduce until they are between 8 and 13 years old, and then do so every 2 to 3 years. Females are not sexually mature until between 10 and 16 years of age, and only reproduce every 4 to 6 years (1). Individuals of up to 48 years old have been recorded; however, the typical life expectancy is around 38 years, and even this may be somewhat optimistic (2).
Spawning takes place between April and June, when the waters are warm enough. There are two distinct forms of this fish, based on their migratory habits. One type is anadromous, migrating up river from the sea to spawn. The larvae of anadromous fish then drift downstream with the flow of the river, and juveniles spend their first summer in the sea, where they remain until fully mature. The second form of the Russian sturgeon is now considered to be extinct, but was an entirely freshwater variety that did not migrate, and was found in the Volga, Danube, and Ural rivers (7).
Within the anadromous form, both autumn and spring migration runs occur, so yet another distinction can be made based on these migratory patterns. Individuals that migrate upstream in spring spawn in the lower levels of the river, whereas those that migrate during autumn spend the winter in freshwater, spawning further upstream during the following spring (1).
The Russian sturgeon feeds on a wide range of organisms, including crustaceans, molluscs and small fish (1).
The Russian sturgeon faces many serious threats to its survival. Vast areas of spawning ground have been lost due to the damming and exploitation of river systems throughout its range, and pollution in the Caspian and Black Sea basins is causing devastating hormonal imbalances, and a greater number of hermaphroditic individuals (1) (8).
The demand for both flesh and caviar is a major threat to almost all sturgeon species, and the caviar of the Russian sturgeon is one of the most sought after. Poaching is incessant, with the illegal catch surpassing the legal quota by far. The Russian sturgeon is also a victim of bycatch (1) (8).
Although there is a restricted sturgeon fishing season and a license to fish is necessary in most of the countries within its range, the Russian sturgeon remains largely un-protected in most of the areas in which it occurs. For example, the absence of a strict monitoring system makes controlling fishing very difficult. Iran has banned private sturgeon fisheries, but, in general, conservation measures are either absent, weak, or ignored (1).
Despite continuous restocking efforts and the creation of artificial spawning grounds, as well as fish lifts to help fish get around dams, the population of the Russian sturgeon continues to decline (1). In a period of just 15 years, global catches have dropped by 98% due to the decline in abundance of this species (9).
Iran and Russia are building gene banks of Russian sturgeon, preserving genetic material by freezing, but the situation for the species in the wild remains precarious (1).
Find out more about sturgeon conservation:
World Sturgeon Conservation Society:
- Anadromous: migratory behaviour of some fish that spend most of their lives at sea, but migrate to freshwater to breed.
- Barbels: fleshy projections near the mouth of some aquatic vertebrates.
- Bycatch: in the fishing industry, the part of the catch made up of non-target species.
- Crustaceans: diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
- Hermaphroditic: possessing both male and female sex organs.
- Larva: immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.
- Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following: a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
- Spawning: the production or depositing of eggs in water.
IUCN Red List (November, 2011)
- Vlasenko, A.D., Pavlov, A.V., Sokolov, L.I. and Vasil’ev, V.P. (1989). Acipenser gueldenstaedtii Brandt, 1833. In: Holcik, J. (Ed.) The Freshwater Fishes of Europe, Vol. 1 Part II: General Introduction to Fishes. Acipenseriformes. AULA-Verlag, Wiesbaden.
CITES (November, 2011)
- Findeis, E.K. (1997) Osteology and phylogenetic interrelationships of sturgeons (Acipenseridae). Environmental Biology of Fishes, 48: 73-126.
- Miller, M.J. (1987) Feeding in the White Sturgeon, Acipenser transmontanus: Ontogeny, Functional Morphology, and Behaviour. MS Thesis, University of Washington.
- Vecsei, P. (2001) Threatened fishes of the world: Acipenser gueldenstaedtii Brandt & Ratzenburg, 1833 (Acipenseridae). Environmental Biology of Fishes, 60: 362.
- Birstein, V.J. (1993) Sturgeon and Paddlefishes: threatened fish in need of conservation. Conservation Biology,7(4): 773-787.
CITES - Acipenser gueldenstaedtii (November, 2011)
FAO Fisheries & Aquaculture (November, 2011)