New Information about the Ocean Ecology of Sockeye Salmon and Relevance to Populations in the Fraser River, British Columbia

Abstract:
Sockeye salmon (Oncorhynchus nerka) were the third most abundant of the Pacific salmon species caught in both the 2019 and 2020 Gulf of Alaska winter surveys. In 2019, 84% of the sockeye salmon catch was in the northwestern area of the survey area, an area not fished in 2020. In both years some sockeye salmon were caught in the southwestern region of the study. In 2019, additional sampling was conducted west of the study area in the central Pacific prior to the expedition and included catches of sockeye salmon originating from Canada, United States and Russia. The broad distribution of Fraser River Chilko Lake sockeye salmon from coastal regions of British Columbia, through the Gulf of Alaska into the central Pacific Ocean suggests that migration patterns may be more of a dispersion than loops and that this dispersion may be influenced by ocean climate conditions. The complexity that this possibility introduces into management for future stewardship and fishing shows that we need to include an understanding of ocean ecology into the stewardship of all future production. This is additionally highlighted by the similarity of sockeye salmon and pink salmon (O. gorbuscha) diet, although there is very little overlap in their distribution, indicating minimal competitive interactions during these winters. Although there remains much to learn about sockeye salmon during their residence in the high seas, the mixed stock catch throughout the region and comparisons with sockeye salmon returns to British Columbia suggest that catch in the winter, specifically of first winter sockeye salmon, may provide an early estimate of relative returns of sockeye salmon two years later.