Interannual variability in the primary and secondary productivity of the Salish Sea and its implications for juvenile salmon

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We propose to study the physical drivers of spatial and interannual variability in phytoplankton and zooplankton production in the Strait of Georgia in order to better understand and predict bottom-up forcing of resident and migrating salmon populations in the Salish Sea. The period after juvenile salmon transition from fresh water to the open ocean has been identified as a period of elevated vulnerability. Prey availability at that time could therefore be a determining factor in overall salmon survival. Phytoplankton growth forms the base of the food chain, and changes in phytoplankton production have the potential to cascade up the food chain to impact salmon. We will use a coupled physical-biological model to investigate mechanisms through which physical drivers affect phytoplankton productivity and the extent to which the resulting changes in phytoplankton productivity propagate up the food chain. In particular, we will seek to identify the drivers of variability in salmon prey at the times and locations most critical to salmon survival. The research plan has been developed in conjunction with the Pacific Salmon Foundation and aims to further understanding of drivers of bottom-up forcing of salmon population dynamics on the west coast of Canada through model-based experiments informed by related observational studies also supported by the Pacific Salmon Foundation. Collaboration with the Pacific Salmon Foundation brings added value to our research through a refined focus on questions bearing on salmon survival and therefore of cultural and economic importance to Canada and through the incorporation of our research in a broader network of projects on related themes, sharing data resources and rapidly communicating finds. BC salmon are iconic species of major importance for commercial, recreational, and First Nation fisheries. Despite major declines over the last decades, recreational salmon fisheries alone generate more than $1 billion annually in BC while generating more than 10,000 jobs. Rebuilding the populations to recent historic levels will thus have major economic, social, and cultural impacts.