Fraser River sockeye salmon: data synthesis and cumulative impacts

Status only data setsIn many cases the data for particular stressor only included an estimate of the current status. Wecould not incorporate these data into the regression analysis. It is not possible evaluate the effectof a particular stressor on sockeye productivity over time if there is no information on how thatstressor has been changing over the time period in which sockeye productivity has beenchanging. With status only data sets, it is not even known whether the stressor has beenincreasing or decreasing.Model setsCandidate model sets were built around the conceptual model (Figure 3.3-1). We consideredmultiple sets of hypotheses, each set designed to answer particular questions. Each of these“series” (arbitrarily ordered and named) and its relevant question(s) of interested are describedbelow and listed in Table A3.5-3A-series) Life history bottlenecks: identify all stressors that are hypothesized to affect aparticular life history stage and add and remove these togetherQuestion: Which life history stages have the greatest effect on productivity over thewhole sockeye life cycle?B-series) Stressor category: add and remove suites of similar stressorsQuestion: Which categories of stressors (organized by the same categories as the CohenCommission Technical Reports) have the greatest effect on productivity over the wholesockeye life cycle?C-series) Geographical regions: identify all stressors that are hypothesized to occur in aparticular geographic location and add and remove these together. Only one particular casewas explored.Question: Which is the more important factor in explaining the observed variability insockeye productivity: marine conditions in the Strait of Georgia or marine conditions inQueen Charlotte Sound 21 ?D-series – L-series) Each of these model sets considers factors within a particular life historystage or combination of life stages (e.g. marine life history stages).Question: Within a particular life history stage, which stressors have the greatest effecton productivity over the whole sockeye life cycle?21 The rationale for this question is thoroughly described in Section 4.4.5.214