Oceanographic conditions within the main area of walleye pollock

Purpose: to characterize oceanographic conditions and their variability at various time scales within the walleye pollock area, including all Far Eastern seas of Russia, the Chukchi Sea, and the South Kuril and East Kamchatka regions.Methods: analysis of literary sources and data of expedition studies conducted by the Far Eastern branches of «VNIRO».Novelty: for the first time, a generalization of current information on the oceanological conditions of walleye pollock habitat in the main areas of its reproduction, feeding and fishing was given.Results: In the Bering Sea, three periods were identified during 1950–2020: cold period (1950–1976), moderate period (1977–2013) and warm period (2014–2020). Strong year-classes of walleye pollock were formed only over the moderate period. During the modern warming of the Bering Sea migrations of walleye pollock from the US EEZ into Russian waters occurs by one month earlier that favors the pollock fishery in the Navarin area and Gulf of Anadyr. The warming of Okhotsk Sea waters, combined with the tendency to reduction of its ice cover, favor expansion of the walleye pollock feeding area northward and westward. The warming of the Sea of Japan results in a depressive trend for all Japan Sea walleye pollock populations. At the same time, against the background of depression in modern (abnormally warm) conditions, the formation of single strong year-classes of any Japan Sea walleye pollock population is still possible.Practical significance: the results of this work can be used to improve the methods of the medium-r ange and long-range forecasts of walleye pollock catch.