Siberian sturgeon

Siberian sturgeon
Conservation status
Endangered  (IUCN 2.3)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Acipenseriformes
Family:	Acipenseridae
Genus:	Acipenser
Species:	A. baerii
Binomial name
Acipenser baerii J. F. Brandt, 1869
Subspecies
A. baerii baerii A. baerii baicalensis Nikolskii, 1896
Synonyms
A. baerii stenorrhynchus Nikolskii, 1896

The Siberian sturgeon (Acipenser baerii) is a species of sturgeon in the Acipenseridae family. It is most present in all of the major Siberian river basins that drain northward into the Kara, Laptev and East Siberian seas, including the Ob, Yenisei (which drains Lake Baikal via the Angara River) the Lena and Kolyma rivers. It is also found in Kazakhstan and China in the Irtysh River, a major tributary of the Ob. The species epithet was named for the German Russian biologist Karl Ernst von Baer.

Taxonomy

Siberian sturgeon is typically subdivided into two subspecies.^[1] However, recent studies suggest that Siberian sturgeon may be monotypic, forming continuous genetically connected populations throughout their vast range.^[2]

The nominate taxon (A. baerii baerii) accounts for 80% of all Siberian sturgeon and resides in the Ob river and its tributaries. This subspecies migrates to mouth of the Ob river during the winter due to seasonal oxygen deficiency in the Ob River, and swim thousands of kilometers upstream to spawn.

The subspecies A. baerii baicalensis known as the Baikal sturgeon is a unique lake form found primarily in the northern end of Lake Baikal and migrates up the Selenga River to spawn.

A third form, "A. baerii stenorrhynchus", resides in the eastern Siberian rivers and displays two life history patterns: a more abundant migratory one which swims considerable distances (sometimes thousands of kilometers) upstream from estuaries and deltas to spawn, and a non-migratory form. This form is now considered to be a junior synonym of A. b. baerii.

Description and population status

Siberian sturgeon usually weigh approximately 65 kg, with considerable variability between and within river basins. The maximum recorded weight was 210 kg. As with all other acipenserids, the Siberian sturgeon are long-lived (up to sixty years), and late to reach sexual maturity (males at 11–24 years, females at 20–28 years). They spawn in strong current main stem river channels on stone or gravel substrates.^[1]

The Siberian sturgeon feeds on a variety of benthic organisms such as crustaceans and chironomid larvae.

The species had been in steep decline in its natural range due to habitat loss, degradation and poaching.^[1] Up to 40% of the Siberian sturgeon spawning habitat has been made inaccessible by damming. High levels of pollution in certain places has led to significant negative impacts on the reproductive development of gonads.^[3]

Aquaculture

While wild catches of Siberian sturgeon have been generally declining, the Siberian sturgeon is increasingly farmed both for meat and to produce caviar from its roe. Because the Lena population of A. baerii completes its life cycle in freshwater and sexually matures relatively early, it is the most commonly original broodstock for captive bred specimens. The main producer of Siberian sturgeon caviar is France, while the largest meat producers are Russia and China.^[4]

Female Acipenser baerii farm bred in Les, Vall d'Aran, Spain

References

Sources and links

• G. I. Ruban, Siberian Sturgeon Acipenser baerii Brandt (Species Structure and Ecology) (GEOS, Moscow, 1999) [in Russian].
• Acipenser baerii - IUCN assessment
• CITES Siberian Sturgeon (Acipenser baerii)
• FAO fact page on Acipenser baerii aquaculture.