Fraser River sockeye salmon: data synthesis and cumulative impacts

the conceptual model?Response: Our conceptual model (Figure 3.3.-1) is meant to provide an overview of thepotential interactions amongst purported stressors to a broad set of audiences for thisreport, that include (in order of priority): Judge Cohen, Commission staff, Commissionparticipants, the public, and scientists. At the Nov. 30 to Dec. 1 workshop, a similar draftconceptual model was presented – all of the participants who provided feedback suggestedthat this model was already too complex for the target audiences (as noted in Appendix 6).We nevertheless decided to maintain that level of complexity in this report to illustrate thefactors potentially affecting each life history stage, as discussed within the CohenCommission technical reports. We believe that adding more complexity to Figure 3.3-1 assuggested (i.e., feedback loops, +, -, +/- along each arrow), while very helpful for building aquantitative model, would be inappropriate for the intended purposes and audience. Wehave however updated the caption on Figure 3.3-1, and redrafted Figure 2.3-1 to reflect theimportant processes you describe.The linear, correlative approach taken in the report has failed to explain much in theway of salmon population dynamics despite decades of work. In fact, prominentscientists have doubted our ability to link recruitment to environmental factors for morethan two decades. Myers (1998), for example, raised such concern based on dismalperformance of correlations in his re-analysis of over 50 recruitment-environmentcorrelations: "The utility of spending large amounts of public research funding toestablish predictions of recruitment based upon environmental indices should thereforebe questioned (Walters and Collie 1998; Walters 1989)". It appears that theseinfluential works in fisheries science were not consulted at all for this report even thoughthe core topics are the same.Response: It isn’t clear from these comments whether you are referring to our qualitativesyntheses of evidence, our quantitative data analyses, or both. We’ll address each in turn.Qualitative syntheses of evidence. Thank you for reminding us of these papers (Walters andCollie 1988, Walters 1989, Myers 1998), and the very real constraints on predictingrecruitment of fish populations. These will be useful to work into the introductoryparagraph to section 3.1. All three of these papers are focused on the difficulties ofpredicting recruitment of fish populations for the purposes of fisheries management,including the lack of persistence of environment-recruitment correlations. We agree withthese authors’ conclusions and indeed emphasized these very challenges in section 3.1,where we noted the inaccuracy of pre-season predictions of sockeye returns (as evaluatedby English et al. 2011). However, our qualitative synthesis is not focused on predictingfuture recruitment; it is a retrospective ecological risk assessment or RERA. As we note insection 3.3.5 when describing our RERA approach: “Because this method is an inherentlyretrospective form of analysis, the results cannot be used to make future predictions.” OurRERA approach seeks to reduce the likelihood of factors which show weak evidence ofexposure, and weak / no correlations with observed patterns of changing sockeyeproductivity; we are not attempting to predict recruitment with those covariates which138