Tuesday, August 11, 2009

Sterlet (Acipenser ruthenus)

This relatively small member of the sturgeon family permanently inhabits freshwaters. It has a long and pointed snout and branched barbels. Like other members of this family, it also lives close to the river bed. It spawns in May in strong currents on a gravelly base, whilst in autumn and spring it congregates in the deep hollows of the river bed. It reaches a length of 125 cm and a weight of 6 to 7 kg. Its diet consists of the larvae of the mayfly, caddis fly and other insects. It has a regional economic importance as it is also reared in carp ponds, where crossbred varieties usually grow faster than the parent species.

It lives in the tributaries of the Black, Azov and Caspian Seas and the Arctic Ocean from the River Ob to the Kolyma. It can also be found in the river estuaries of the Baltic Sea, such as that of the Dvina. In the Danube it reaches as far as the Passau and on rare occasions the rivers Isar and Salzach. Along the coastline and estuaries of the Arctic Ocean it has evolved into an independent species, which differs significantly from the other types of sturgeon found in the river tributaries of the Baltic, Black, Caspian and Azov Seas.

Sterlet (Acipenser ruthenus)

Maximum size and weight: 150 cm, 16 kg.

Identifying characteristics: Long and pointed snout; long, branched barbels. Back has 11-17 bony plates with long, sharp, hook-like thorns

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