Influence of climatic factors on interannual variations of Kamchatka pink salmon stocks in 2014–2020

Abstract

The high heat content of surface waters in northern North Pacific and Far Eastern Seas in 2014– 2019 has resulted in the formation of extremely favorable environmental conditions for pink salmon spawning in the Kamchatka rivers, at all stages of marine period of their life cycle. The growth of Far East pink salmon catches in 2014–2018 was associated to a great extent with an unusual increase in the catch of even-year generations of East Kamchatka pink salmon, which were not dominant for this stock. In 2018, their share in the total catch of Russian pink salmon reached almost 22%, while in 2006–2010 it did not exceed 3–6%. The growth of catches of evenyear generations of East Kamchatka pink salmon in 2014–2018 coincided with an anomalous decrease in the ice cover in the Bering Sea and shift of its border far to the north. The return of thermal and ice conditions in the Bering Sea and the near-Aleutian region to the mean long-term level in the winter of 2019/2020 obviously contributed to the less favorable survival conditions for the 2018 East Kamchatka pink salmon generation and recovering of the «sawshaped» variations of biomass observed during the recent decades and, as a result, the similar variations of catches, with their high volumes in odd years and low volumes in even years.