Monitoring the biological condition of juvenile Fraser sockeye in relation to stock-specific survival

The unpredictability and variation in adult recruits for Fraser sockeye both within and among major stocks cause challenges for harvest planning and rebuilding initiatives. This multi-year project will monitor and analyze variation in biological condition of juvenile sockeye in fresh water to understand variation in stock-specific survival. This project will apply and extend the results from a previous SEF juvenile sockeye research project that found stock-specific energetic condition of juveniles reflects variation in lake primary productivity and density of juveniles within a natal rearing lake. Moreover, mechanistic links to survival were developed, such as, interannual variability in fall-fry and smolt energetic condition are consistent with density-dependent growth and survival, critical minimal energy levels are associated with swim performance and potentially survival, and interannual and stock-specific variability in the portion of individuals at or near these critical energy levels. We propose to extend and apply these results by strategically assessing stock-specific variability in biological condition of juvenile salmon from key Fraser sockeye stocks.

The outcomes of this work will advance our understanding of the connection between habitat quality and juvenile energy dynamics in relation to survival, thereby contributing to improved knowledge of the interacting factors that limit sockeye survival in freshwater lakes, as well as helping to predict early marine survival of Fraser sockeye on population specific basis. We will apply these results to make explicit scientific advice relevant to habitat capacity and spawning escapement targets, to the utility of specific restoration/rebuilding activities, and contribute science information on fish condition to preseason forecasts for harvest plans for different stocks.