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 li ...

in the family

Acipenseridae Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...

found in the

Amur River The Amur (russian: река́ Аму́р, ), or Heilong Jiang (, "Black Dragon River", ), is the world's List of longest rivers, tenth longest river, forming the border between the Russian Far East and Northeast China, Northeastern China (Inne ...

basin in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. 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, it h ...

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 The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

. 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.

Habitat and ecology

References

Further reading