Fraser River sockeye salmon: data synthesis and cumulative impacts

Stage 5: Migration back to SpawnWhile the timing of en-route mortality coincides generally with the Fraser sockeye situation,the Fraser sockeye productivity indices already account for en-route mortality (i.e., recruits =spawners + harvest + en-route mortality). Therefore, there is no point in examining correlationsbetween en-route mortality and life cycle or post-juvenile productivity indices within the samegeneration. The only possible effects on productivity indices are inter-generational effects, forwhich the evidence is limited and equivocal. We therefore conclude that it is unlikely that enroutemortality (or pre-spawn mortality, which has only increased for Late Run sockeye) are aprimary factor in declining indices of Fraser sockeye productivity. However, en-route mortalityhas definitely had a significant impact on the sockeye fishery and the numbers of adult fishreaching the spawning ground, particularly for the Early and Late runs. Pre-spawn mortality,habitat changes, and contaminants are unlikely to be responsible for the overall pattern ofdeclining sockeye productivity. No conclusion is possible regarding pathogens due toinsufficient data. None of the factors assessed for this life history stage are likely to have shownsignificant changes between 2009 and 2010.The above conclusions are based on qualitative and quantitative analyses of existing information.There are two important caveats on these conclusions. First, there are major gaps in both ourfundamental understanding of how various factors interact to affect Fraser River sockeyesalmon, and in the data available to quantify those factors. Second, all Cohen Commissionresearchers have had a limited amount of time to analyze existing information; future datasyntheses and analyses will likely provide deeper and different insights. Below, we summarizeour recommendations for improving the data and understanding of Fraser River sockeye salmon.5.2 Research and Monitoring PrioritiesOur summary of research and monitoring priorities includes findings from both the workshopinvolving all Cohen Commission researchers (held Nov. 30 – Dec. 1, 2010), and our synthesis ofthe more detailed recommendations contained in the Cohen Commission’s technical reports.5.2.1 Results from the workshopWorkshop participants were asked to examine section 5.3 of the Expert Panel’s Report to thePacific Salmon Commission (PSC report), Priorities for Monitoring and Research (Peterman etal. 2010), as a starting point for a plenary discussion. Since each of the twelve projects containsrecommendations specific to their topic areas, the purpose of this exercise was to broadly addresspriorities for monitoring and research beyond project boundaries.103