Impact of modern changes of oceanographic conditions in the Sea of Japan on state of the Primorye pollock population
2018
Zuenko, Yu.I. | Nuzhdin, V.A.
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
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