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Fraser River sockeye salmon: data synthesis and cumulative impacts

Fraser River sockeye salmon: data synthesis and cumulative impacts

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Figure A3.5-2. This is an example of residual diagnostic plots used to assess the fit of a piece-wise regression modelwith two straight lines for Stellako productivity (i.e., ln(R/S)). The most likely model suggests a changepoint in 1985 (brood year).Stock portfolio summariesSchindler et al. (2010) found that stock composition plays an important role in the overallvariability of a regional stock complex (in their case Bristol Bay <strong>sockeye</strong>). In particular theyfound that having a portfolio of many stocks results in less variability across the whole regionalstock complex, than if the portfolio was represented by only a few individual stocks. The <strong>Fraser</strong><strong>River</strong> Sockeye regional stock complex consists of 36 Conservation Units (CUs) (refer to theFreshwater Technical Report (# 3) for CU status assessments). We were interested in finding out,for the 19 stocks where we have <strong>data</strong>, how balanced the portfolio of <strong>Fraser</strong> <strong>River</strong> <strong>sockeye</strong> stocksis. Additionally, we were interested to see whether that balance has changed over time. We used207

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