Using hierarchical models to estimate effects of ocean anomalies on north-west Pacific Chinook salmon Oncorhynchus tshawytscha recruitment

Authors

  • R. Sharma,

    Corresponding author
    1. Columbia River Inter-Tribal Fish Commission, 729 NE Oregon St, Suite 200, Portland, OR 97232, U.S.A.
      Tel.: +1 503 736 3590; fax: +1 503 235 4228; email: shar@critfc.org
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  • M. Liermann

    1. Fish Ecology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E, Seattle, WA 98112, U.S.A.
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Tel.: +1 503 736 3590; fax: +1 503 235 4228; email: shar@critfc.org

Abstract

The high variability in survival over the past three decades of north-west Pacific Chinook salmon Oncorhynchus tshawytscha is summarized for 24 stocks and analysed using hierarchical Bayesian models. Results from a simple model indicate that recruitment anomalies appear to be correlated in time and space. A simple model with a covariate based on basin-scale effects (Pacific Decadal Oscillation and El Niño Southern Oscillation) and local-scale effects (sea surface temperature, SST anomaly) was introduced to explain this variability. The model still exhibited residual patterns that were removed when a random-walk component was added to the model. The analysis indicates that recruitment is negatively related to SST anomaly for all stocks and the effect of basin-scale variables is negligible. The effect of climate over the next century is expected to result in estimated recruitment declining by an average of 13% for O. tshawytscha stocks coastwide.

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