Improvements to Fraser River Pink Salmon Run Reconstruction Models and In-Season Assessments

Fraser River pink salmon returns have been notoriously difficult to assess in-season. Many of the assessment tools originally developed for sockeye salmon do not perform well for pink salmon due to slower and more variable migration speeds. Small and highly variable catchability coefficients add additional uncertainty to pink salmon run size estimates based on test fishery catch-per-unit-effort (CPUE) data. While there is potential to improve in-season estimates using commercial catch indices (e.g. Area 7) in a reconstruction framework, the current data structure does not easily support a thorough investigation of this type of analysis. In 2019, atypical migration behaviour resulted in significant assessment challenges. Due to an incorrect alignment of test fishery and commercial CPUE data, pink salmon run reconstruction models underestimated the true run size. Both the data integrity and underlying model assumptions were scrutinized post-season and a clear need for model upgrades was noted by the Fraser River Panel and Technical Committee. The result of this project will be a more robust, and accurate in-season assessment tool for Fraser River pink salmon and future improvements in meeting management targets.