Using Hierarchical Models to Estimate Effects of Ocean Anomalies on North-west Pacific Chinook Salmon Oncorhynchus tshawytscha Recruitment
The high variability in survival over the past three decades of north-west Pacific Chinook Salmon Oncorhynchus tshawytscha is summarized for 24 stocks and analyzed 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 Nino 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.
Sharma, R. and M. Liermann. 2010. Sequence using hierarchical models to estimate effects of ocean anomalies on North-west Pacific Chinook Salmon Oncorhynchus tshawytscha recruitment. Journal of Fish Biology 77(8):1948-1963. Online at https://doi.org/10.1111/j.1095-8649.2010.02779.x.