Seasonal Migrations of Pacific Cod Gadus macrocephalus (Gadidae) off the Eastern Coast of Kamchatka

摘要

On the basis of materials of bottom trawl surveys of , data of commercial statistics of , as well as literature sources, on the dynamics of seasonal distributions of cod Gadus macrocephalus and its migrations off eastern Kamchatka are studied. In the southeastern part of the shelf of the peninsula, from Cape Lopatka to Kronotskii Bay inclusively, as compared to its northeastern part, in the cold period of the year, a considerable increase in the density of distribution and the commercial catch of the cod are recorded. In the warm period, the density of its distribution and catch, on the contrary, are higher in the northeastern part of the Kamchatka shelf, in Kamchatka Bay, as well as in the Karaginskaya commercial subzone. This suggests that the cod performs rather extended seasonal migrations during which its considerable part winters and spawns off the southeastern coast of Kamchatka and feeds off the northeastern coast, in Karaginskii and Olyutorskii bays, and, possibly, more to the northeast. At the same time, a noticeable part of cod does not perform extended migrations and throughout the year inhabits eastern Kamchatka bays and adjoining waters. Both types of migratory behavior are characterized by seasonal changes in the habitation depth: in the warm period of the year, cod inhabits comparatively small depths near the coast and, in the cold period, comparatively large depths in the external part of the shelf and the upper section of the continental slope.