The Endangered Eurasian Freshwater Sturgeons

Abstract

Siberian sturgeon Acipenser baerii, Amur sturgeon A. schrenckii, kaluga Huso dauricus and sterlet A. ruthenus are Eurasian sturgeon fish species that live mainly in fresh water. They are distributed (except for sterlet) exclusively on the Asian continent: Siberian sturgeon inhabits the basins of all major rivers of Siberia that flow into the Arctic Ocean from the Ob' River to the Kolyma River inclusive. Amur sturgeon and kaluga occur in the Amur River basin and the Amur estuary, sometimes recorded in the coastal waters of the Sea of Okhotsk and the Sea of Japan. Sterlet is distributed in the basins of large rivers flowing into the Black, Azov, Caspian, White, Barents, Baltic and Kara seas. These are delicious, valuable commercial fish species, the catches of which in the late 19th—early 20th century reached hundreds of tons. Kaluga, Siberian and Amur sturgeon are large fish; the sterlet is the smallest representative of the family Acipenseridae. They are characterized by late maturation and non-annual spawning, which causes a low level of natural reproduction. In the 20th century, there was a catastrophic decline in their numbers and a reduction in their ranges, primarily as a result of excessive fishing load (including poaching), the loss of available spawning grounds as a result of hydraulic engineering, as well as water pollution. Currently, their catches in the wild are extremely small. The species are listed in Annex II of CITES, Annex II to the Bonn Convention, the Red Books of various countries, as well as in the IUCN Red List: Siberian sturgeon as an endangered species, Amur sturgeon and kaluga as critically endangered species, sterlet as a vulnerable species. To preserve these valuable fish species and increase their number, it is necessary to strengthen their protection in spawning and wintering areas, as well as to intensify artificial reproduction.