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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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Bristol Bay review: There are substantial differences between the <strong>Fraser</strong> <strong>and</strong> Bristol Bayfisheries. The latter has fewer fisheries, gear types <strong>and</strong> sectors, less mixed-stock fishing issues,very small sport <strong>and</strong> First Nations subsistence harvests <strong>and</strong> few in-river fisheries. Area managershave very timely <strong>and</strong> accurate <strong>data</strong> on catch <strong>and</strong> escapement, clearly-defined escapement goalsthat vary little between years <strong>and</strong> unambiguous authority to open <strong>and</strong> close fisheries.Their pre-season forecasts in some cases are not as good but they rely mostly on in-seasonmanagement. Their performance in meeting escapement targets has been pretty good in terms ofstaying above minimum escapement levels <strong>and</strong> usually in the range close to the upper target.Information/evidence gaps: These include uncertainties around en route losses. Given thepotential scale of the latter (greater than total escapement or total catch in some years), this isprobably much more of an issue than the amount that they are off with the estimates of catch <strong>and</strong>escapement, which are not perfectly monitored but pretty reliable estimates. The numbers for enroute losses are best guess based on very limited <strong>and</strong> questionable <strong>data</strong>.DiscussionStaley: Where the quality of <strong>data</strong> is unknown, it may be unknowable or simply unknown becauseno one has done the work. You should distinguish between the two.English: For commercial fisheries, there are aerial surveys <strong>and</strong> reported catch rates. You can getreasonable estimates of effort for some gear types <strong>and</strong> catch rates. There is no estimate ofprecision <strong>and</strong> no verification but a good proportion of the fleet is reporting. We could try toverify the <strong>data</strong> but the challenge is getting the information from FOS (DFO’s FisheriesInformation System) in time for this project.Staley: Re the pre-season forecasts, it’s surprising that the performance of the forecast for total<strong>Fraser</strong> <strong>sockeye</strong> run size is not significantly better than that for individual stocks.English: The median absolute percent error was lowest for the overall <strong>Fraser</strong> run.Peterman: The r-squared values in the bar graph “significance of forecast vs. return relationship”seem high.English: The <strong>data</strong> were from a document that shows pre-season <strong>and</strong> post-season numbers.Peterman: The pre-season <strong>data</strong> may actually be in-season estimates, so check that those areactually the pre-season forecast numbers because I’ve never seen a correlation that high forforecasting on the <strong>Fraser</strong>.That could also be that it’s based on <strong>data</strong> going back to the 1950s, not just the last 30 years.Cox: How are en route losses calculated?English: For some, it’s based on Mission counts against spawning ground counts minus catch.For some recent years, estimates are based on telemetry <strong>data</strong>.Cox: How does that figure in calculating recruits per spawner?English: Total returns are based on catch, escapement <strong>and</strong> en route mortality.McKinnell: Highly cyclic stocks have high r-squared because of the contrast between very high<strong>and</strong> very low years.37

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