Arctic cisco (Coregonus autumnalis)
The Arctic cisco for feeding uses not only river mouths and bays, but also the entire coastal zone of the polar seas, withstanding the salinity up to 2.0-2.2 % and even higher. In the sea it feeds on crustaceans and juvenile fish. The Arctic cisco becomes sexually mature at the age of 6-8 years when it reaches the length of 35 cm. It is running up the rivers for spawning, sometimes – up to 1,500 km; the breeding takes place in October. The fecundity is from 16 to 60 thousand eggs, more often from 20 to 30 thousand eggs. After spawning, it goes back into the sea; some specimens spawn 2-3 times during their life.
The usual length of Arctic cisco in catches is not more than 40 centimeters, weight up to 1 kilogram. There are individuals up to 64 cm long and weighing up to 3 kg. The closest relative of the Arctic cisco, Baikal cisco, dwells in Lake Baikal and is described as a subspecies. It is smaller comparing to the fish from anadromous stocks. In the Lake Baikal, several ecological forms (races) of Arctic cisco are distinguished, which differ in feeding areas and spawning tributaries.