Improving Terminal Abundance Estimates of Spring- and Summer-run Age 5₂ Fraser River Chinook Salmon by Incorporating a Second CPUE Dataset from the Albion Test Fishery

Abstract Excerpt:
Fraser River Chinook salmon (Oncorhynchus tshawytscha) are currently managed as five stock aggregates that share similar ages and return timing (Fig. 1). An in-season Bayesian model has been used since 2012 to estimate the total abundance of two of these aggregates: spring- and summer-run age 5₂ Chinook. This model predicts the terminal aggregate abundance to the mouth of the Fraser River using cumulative weekly catch-per-unit-effort (CPUE) from the Albion test fishery and reconstructed annual run size. These predictions are used as an in-season tool to manage Fraser River fisheries in line with the expected abundance of the aggregated spring- and summer-run age 5₂ Chinook via a “zoned” approach (DFO 2018). The abundance of these aggregates has been declining in recent years, and it is critical to improve the precision of the in-season model for sustainable fishery management.