Environmental surrounding of pink salmon juveniles during fall and winter 2019/2020
2021
Naydenko, S.V. | Khen, G.V. | Figurkin, A.L. | Kuznetsova, N.A. | Starovoytov, A.N. | Somov, A.A. | Shebanova, M.A.
Several significant forecast failures occurred during 2020 pink salmon (Oncorhynchus gorbuscha) fishing season in Russia. The major crush was observed for eastern Kamchatka. Precarious harvest was also observed for some Alaskan stocks. This paper represents an opposing representation of environmental and feeding condition during pink salmon offshore migration and wintering in 2019–2020 which were considered as unfavorable according to several authors. A comparison of 2019 prey composition and feeding intensity with long-term data showed that feeding conditions were sufficient. The feeding conditions in the fall of 2019 could not be the reason for the low returns of pink salmon in 2020. Analysis of environmental conditions (configuration of the western subarctic gyre, temperature distribution, position of isotherms, ecology and abundance of zooplankton species) demonstrated no significant difference with previous years. Therefore, in our opinion, the dramatic thermal regime shift during the winter 2020 in the North Pacific which caused structural changes biomass decrease in zooplankton communities and, consequentially, deterioration of the feeding conditions, seems quite doubtful
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