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 Northwest Pacific Chinook Salmon Oncorhynchus tshawytscha Recruitment. Journal of Fish Biology 77:1948-1963.