Conclusions
Given potential reductions in favourable habitat due to accelerating global warming, there is an urgent need to better understand the ocean environment experienced by salmon and how this impacts their health and condition. Up to now, little information has been available on stock-specific salmon distribution which hampers our ability to resolve stock-specific dynamics and develop appropriate management plans. The marine environment is heterogeneous, and populations foraging in different areas may be affected in different ways as environmental conditions change. In this study, we showed that salmon stocks with geographically close rearing grounds can have different at-sea distributions, potentially driven by the difference in ocean entry timing and size. Expanding this approach with data from other major sockeye stocks and other salmon species would improve understanding of the mechanisms explaining salmon spatial distribution in the high seas, and how this distribution interacts with environmental conditions to affect salmon survival and fitness.