Scale Analysis of Puget Sound Chum

The objectives of this project are to 1) identify environmental and biological factors related to variation in marine growth and productivity of Puget Sound Chum salmon (Oncorhynchus keta); and 2) develop stock specific indicators of productivity and survival based on marine growth and environmental indices for forecasting. Previous research examining early marine growth and survival of Puget Sound Chinook salmon (O. tshawytscha) in relation to biological and environmental factors provided an approach to understanding mechanisms related to mortality during the marine period (Campbell et al. 2017, Claiborne et al. in prep). The result of this work is a useful tool used for forecasting fall Chinook salmon in South Puget Sound (WDFW Puget Sound Management Unit, unpublished data). This proposal will generate early marine growth estimates from scale analysis of archived samples (WDFW Fish Ageing Laboratory) for fall-run Chum salmon for 15 brood years and relate early marine growth to trends in productivity and survival throughout Puget Sound. To assess bottom-up and top-down processes that may be driving variation in productivity, we will examine relationships between marine growth and environmental indices, which will include both large- and regional-scale metrics. For each stock, we will develop predictive models of productivity and survival incorporating environmental indices and annual growth estimates, and use hind-casting to evaluate model performance through time.