Year-to-year dynamics of recruitment is considered for the Primorye population of walleye pollock (northwestern Japan Sea, with the main spawning ground in Peter the Great Bay) on the data of bottom trawl surveys. It has a negative tendency and 5-11-years cyclic fluctuations reasoned by negative relationship between the recruitment and stock because of overloading the carrying capacity of the biotope for the species. This relationship is approximated by nonlinear function with the parameter, of carrying capacity that is negatively depended on water temperature in the pollock habitat (Intermediate water mass). Besides, the abundance of 1-2 strong year-classes, which form once in a cycle in conditions of the minimal stock, depends directly on winter SST, negatively as well. Frequency of these strong year-classes appearance also depends on carrying capacity: the larger the capacity -the shorter the cycles and more frequent the blooms. Modern environmental changes distinguished by warming of all layers in the Japan Sea, in particular in the intermediate layer, are unfavorable for the pollock reproduction because of the carrying capacity decreasing. On the base of these regularities, using a simple population model, the pollock stock changes in the next decade are forecasted: the stock growth is expected until 2019 when it will exceed 100,000 t, then it will go down below 80,000 t in the middle of 2020s, and possibly will not restore again if warming of the Intermediate water will continue.
Recent changes in reproduction are considered for two populations of walleye pollock which spawn in the Japan Sea at the coasts of Primorye and Hokkaido. Interannual dynamics of reproduction for both populations corresponds to the stock-recruitment dependence described by Ricker curve that determines the maximum recruitment with an optimal value of stock equal to the carrying capacity of the biotope for the species and the lower recruitment if the stock is either lower or higher than this optimal value. However, instability of the Ricker curve parameters is noted, and their recent changes were unfavorable for reproduction of both populations and caused decreasing of their stocks, with sharp decline in the early 1990s. Basing on authors results and cited data, climate change in the Japan Sea region is determined as the reason of this decreasing, in particular weakening of winter monsoon. In spite of a common nature, mechanisms of the climate change influence on two studied populations are completely different: reproduction of the Hokkaido population worsened because of increasing transfer of its eggs and larvae out of the Japan Sea in conditions of the strengthening Tsushima Current, that was explained in the terms of Ricker curve as decreasing of population fecundity, but reproduction of the Primorye population worsened because of unfavorable for pollock reconstructions in the local ecosystem located in the south periphery of the Subarctic zone in conditions of increasing water temperature that was explained in the terms of Ricker curve as shrinkage of carrying capacity for pollock (from approximately 150 .103 t to almost zero level). Note that the carrying capacity did not shrink but slightly extended (to 500 .103 t) for the Hokkaido population located in the north periphery of the Subtropic zone. Features of climate warming influence onto subarctic and subtropic ecosystems are discussed.
В Японском море по данным спутниковой и судовой информации проведён анализ океанологических условий в мае-июне 2000-2017 гг. Спутниковые данные представлены изображениями поверхности моря в инфракрасном и оптическом диапазонах, а судовая информация-глубоководными измерениями температуры и солёности на стандартных океанографических разрезах. По альтиметрическим данным построены карты аномалий уровня моря с целью идентификации геострофической циркуляции весной исследуемых лет. Совместное использование спутниковой и океанографической информации позволило провести трёхмерный анализ океанологических структур (течений, фронтов и их разделов, антициклонов и водных масс). В результате этой работы выполнена типизация весенних сезонов в 2000-2017 гг. на три группы по термодинамике вод и положению океанографических структур на спутниковых картах и океанографических разрезах. Доминирующий признак типизации-термическое состояние вод. Показано, что колебания температуры воды только опосредованно, в первую очередь через биоту, могут влиять на степень выживания минтая на ранних стадиях онтогенеза и формирование численности годовых классов. Ключевые слова: Японское море, спутниковые изображения, океанологические структуры, термодинамика вод, стандартный разрез, температура, солёность, водные массы, минтай Theragra chalcogramma.
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