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Fraser River sockeye salmon: data synthesis and cumulative impacts

Fraser River sockeye salmon: data synthesis and cumulative impacts

Fraser River sockeye salmon: data synthesis and cumulative impacts

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Table A3.5-4. Description of the 6 model sets that were examined as part of this project.Model Set name Description Time period (by Brood year)A4c Comparison across life stages 1969-2001A4bComparison across life stages, with pink 1969-2001<strong>salmon</strong> includedB4c Comparison across stressor categories 1969-2001B4bComparison across stressor categories with 1969-2001pink <strong>salmon</strong> includedC4aComparison of all available marine <strong>data</strong> 1969-2004between SoG <strong>and</strong> QCS. No <strong>data</strong> for QCSSST.C3aComparison of all available marine <strong>data</strong> 1980-2004between SoG <strong>and</strong> QCS. Including QCSSST.C1aComparison of all available marine <strong>data</strong>including chlorophyll for SoG <strong>and</strong> QCSseparately.1996-2004C<strong>and</strong>idate modelsC<strong>and</strong>idate models refer to the list of alternative models compared within each model set. Each ofthe c<strong>and</strong>idate models is fit using the same <strong>data</strong> set. Recall that models may differ in terms of thecombination of stressor covariates <strong>and</strong> the functional form of the model. Covariates could enterthe model in some non-linear way or interactions among covariates could be specified.However, all c<strong>and</strong>idate models should be based on biological hypotheses. We did not feel wehad sufficient knowledge regarding the expected functional form of the relationship between thevast number of covariates <strong>and</strong> the response variable to assume anything beyond the simplestlinear relationship. Possible interactions were also considered based on the information providedby the Cohen Commission Technical Reports <strong>and</strong> our own qualitative <strong>synthesis</strong>. The onlyinteractions that were explicitly discussed in our report were:• Disease/Pathogens & temperature• Disease/Pathogens & pollutants• Disease/Pathogens & l<strong>and</strong> use practices• Sea surface salinity & sea surface temperatureThe first three interactions were impossible to explore given the lack of disease/pathogen <strong>data</strong>.Interactions among marine factors during coastal migration could be explored with existing <strong>data</strong>but were not considered at this time. With more time <strong>and</strong> input from subject experts (e.g.,authors of the other Cohen Commission Technical Reports) the hypothesized links betweencovariates <strong>and</strong> productivity (Section A3.2-A3.4) could be refined <strong>and</strong> added to. Our approach217

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