The Japanese sturgeon, or Amur sturgeon (''Acipenser schrenckii'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

in the family Acipenseridae found in the Amur River basin in China and

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

. Claims of its presence in the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, i ...

need confirmation. The species has 11–16 dorsal, 34–47 lateral, and 7–16 ventral scutes. Their dorsal fins have 38–53 rays and 20–35 anal fin rays. They also have greyish-brown backs and pale ventral sides. The species could reach up to 3 m (9.8 ft) in length, and weight over 190 kg.Description and distribution
The species is considered to be critically endangered.

Habitat and ecology

The Japanese sturgeon is benthic. Their main food sources are aquatic insect larvae, bone fish and mollusks. One study suggests that the type of aquatic insect larvae eaten by juvenile Japanese sturgeon depends on the season, where mayfly nymphs are eaten more frequently in Spring and Fall, and midge larvae are eaten more frequently in Summer. The females mature at 9–10 years of age, and males at 7–8 years. They start to migrate in the autumn. They live for 65 years.

References

* Masuda, H., K. Amaoka, C. Araga, T. Uyeno and T. Yoshino (1984). The fishes of the Japanese Archipelago. Vol. 1 (text). Tokai University Press, Tokyo, Japan. 437 p. (text), 370 pls. *Journal Coll. Sci. Imp.Univ.,Tokyo, "23", (7). *Global Biodiversity Information Facility http://data.gbif.org/species/13576254/. Viewed 27 January 2010. Acipenser Fish of East Asia Freshwater fish of China Fish of Russia Amur basin Fish of Japan Sea of Japan Critically endangered fish Critically endangered biota of Asia Fish described in 1869 {{Acipenseriformes-stub

Habitat and ecology

References

Further reading