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Penzhina cisco (Coregonus subautumnalis)

This interesting whitefish is found only in the Penzhina and Talovka Rivers, which flow into the Shelikhov Bay of the Sea of Okhotsk. In comparison with the Actic cisco, the Penzhina cisco is characterized by strong dependence on the fresh water. The Penzhina cisco is not large; its weight does not exceed one kilogram.

The mouth is terminal; the jaws have equal length. The lower jaw is short (its length is less than the height of the caudal stem). The body is wide, massive; the caudal peduncle is short and high. The scales are large, round, firmly attached.

This whitefish species has small range and therefore is listed in the Red Book of the Kamchatskiy Krai. The diet of this fish in summer and fall consists mostly of zooplankton and different insects.

In summer, the Penzhina cisco live in the channel part of the middle course of the rivers, in the floodplain channels, and in the lakes connected to rivers. It is possible that some individuals make extensive migrations in early summer to the estuary of the Penzhina and Talovka Rivers, and in the autumn – to the spawning grounds in the middle course of the rivers. The numbers of the juveniles reached 300-500 specimens (2.7-4.6 kg) per one hectare in the northern part of Lake Talovskoye. The numbers of the yearlings and older fish was much smaller in number (25-33 specimens/ha), but more in biomass (5.4-7.2 kg/ha).

In catches in the Penzhina River there were specimens in the age of up to 10+ years, the length up to 433 mm and the weight up to 1175 g. In the Talovka River – up to 445 mm and 1565 g. In the Talovka River the species is not only larger than in the Penzhina River, but also grows much faster. The average annual growth in the Talovka River at the age of 3, has reached 84 mm. the spawning takes place in late September and early October at the foothill sections of the rivers with small pebbles and medium flow rate.

The presence of the yearlings, juveniles, and older fish far from the sea distinguishes the Penzhinsky cisco from the Arctic cisco, which is much more strongly associated with marine waters.

Ilya Sherbovich