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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.

Based on the analysis of changes in the spatial structure of climatic variations in the Northern Hemisphere before and after the climatic regime shift in the 1980s, the modes of interaction between climatic processes in the North Atlantic and North Pacific have been identified. The first (“western”) mode prevailed until the late 1980s, reflected the impact of the North Pacific climatic processes on the North Atlantic climate as a result of interaction of two mutually independent Pacific teleconnection patterns (Pacific/North American and Tropical/Northern Hemisphere patterns) with the West Atlantic pattern. The pronounced eastward shift of the North Atlantic Oscillation (NAO) centers from the late 1970s resulted in establishment of the “eastern” mode of interaction between the aquatories under consideration. The climatic changes originated in the North Atlantic basin propagated in the western half of the North Pacific via the system of atmospheric teleconnection patterns over Eurasia (“atmospheric bridge”). The establishment of the “eastern” mode became obviously one of the reasons of sharp warming of surface waters in the western and central areas of the North Pacific from the end of the 1980s, which favored the beginning of a new “salmon epoch” in its northwestern part. Along with the synchronous relationships between the Eurasian atmospheric modes and North Pacific sea surface temperature anomalies, an asynchronous response in the ocean to longitudinal shifts in position of the NAO centers, was found. The atmospheric signal associated with its southern center propagated eastward along the equatorial zone and appeared in the southwestern sector of the North Pacific 5–6 years later.

Purpose: to investigate the features of the long-term dynamics of codfish stocks in the North Atlantic region as a basis for predicting their state and sustainable fishing (exploitation).   Materials: data on spawning stock biomass, abundance of recruitment at age 0 to 3 years, survival indices at early ontogenesis stage for 11 Atlantic cod stocks, 6 Atlantic haddock stocks, and 4 saithe stocks for the period 1946–2020   Methods: a comparative analysis of the above time series based on their statistical processing.   Novelty: For the first time, a 50–60-year cycle which characterizes the long-term variations of the Atlantic Multidecadal Oscillation index, were revealed in the long-term fluctuations of the Northeast Arctic cod recruitment. This assumes a relationship in the long-term variations of two parameters under consideration.   Results: The significant interannual variability of all characteristics was identified for each of the 21 commercial fish stocks under consideration. Statistically significant positive correlations were found between changes in recruitment abundance of Atlantic cod in the Northwest Atlantic and Atlantic cod, Atlantic haddock, and saithe in the areas of Greenland, Iceland, North and Baltic Seas. Changes in the recruitment abundance of Labrador cod and Northeast Arctic cod in the Barents Sea are opposite.   Practical significance: the results of this work can be used to improve the methods of the medium-range and long-range forecasts of codfish catches in the North Atlantic region.