Identification of key metrics collected during first marine year for improving early stock specific forecasting of Fraser River Sockeye salmon

We propose that a combination of the variable ocean conditions between years and the variability in rearing duration in the Strait of Georgia will impact the growth and condition of juvenile Sockeye salmon as they leave the Strait of Georgia, and will influence survival during the first and second marine winters and subsequently total marine survival. This project will utilize sockeye samples collected during both the Mission downstream trapping and nearshore marine sampling in 2017 and 2018 to examine variability in stock specific condition (energy density and prevalence of pathogens). An association study (L. Godbout) will examine early marine growth (otoliths) in these two years. We will work collaboratively with Dr. J. King to include juvenile samples collected in 2018 in QCS in our analysis. In addition we will work with the NPAFC (Riddell and Beamish) winter survey in the North Pacific in February and March 2019 to compare these juveniles with sub-adults captured during their first and second marine winters. Samples of adult returns from dominant stocks will also be collected in 2019 and 2020. This will be the first work examining individual stocks across their entire life history from downstream migration, to early marine growth, high seas residence and spawning return. The results of this work will be used to test the critical size and period hypothesis and to identify indicators of salmon survival that can be measured during the early marine period. These results can immediately be incorporated in qualitative information that is compiled annually in DFO reports on observations across all life-history stages of Fraser River Sockeye to provide an indication of survival for these stocks in an upcoming return year. The goal long-term of this process and these results will be to improve quantitative forecasts of Fraser River Sockeye.