Fraser River sockeye salmon: data synthesis and cumulative impacts

for all CUs should not rule out using existing data, but with caveats, and 3) caution that impactsmay be local and subtle.PICES Advisory Report on the Decline of Fraser River SockeyeSalmon in Relation to Marine EcologySkip McKinnell, PICESThe main objective is to assemble a comprehensive summary of what is known about FraserRiver sockeye salmon in the ocean. Much of the study involved reviewing data/ technical reportsand peer-reviewed literature, although some original data were re-analyzed. To explain the longtermdecline in sockeye salmon, McKinnel presented evidence that there was an abrupt “shift” tolower productivity in 1992 rather than a “trend” of a gradual decline in productivity. The lowreturns of 2009 are associated with the 2007 (2nd lowest) ocean entry year (OEY) for sockeyesalmon. The 2006/7 el Niño created extremes in discharges (runoff) on the central coast of BCthat may have affected the salmon by altering surface salinity. Furthermore, there were unusuallystrong southeasterly winds in the summer of 2007 (the most extreme since 1948), which keptfreshwater entrained in Queen Charlotte Sound (QCS). This raised the sea level and maintained alow salinity, freshwater “lens” in QCS, all of which delayed the spring bloom of algae (the latestsince records began to be collected in 1998). Additional evidence for ocean forcing were warmsurface sea temperatures (SSTs) in QCS in 2007.Data which extend the PSC report include: 1) the 2006 Harrison River brood year returns, 2)2004 Chilko Lake sockeye marine survival, and 3) 2007 weather, climate, oceanography andphenology of Queen Charlotte Sound/Strait. The most important unknowns for sockeye salmonin the ocean are the numbers of smolts entering the sea, by stock. There have been no studiesdocumenting where and when sockeye salmon die in the ocean.This presentation stimulated many questions from workshop participants including:o What’s the relative likelihood of different mechanisms that are not mutually exclusive?o Chums did poorly in 2010 and sockeye well, but both entered ocean in 2007 - why?o Why were conditions more extreme in QCS during 2007 than in Georgia Strait?o Could there have been harmful algae blooms in QCS as suggested in the PSC report?o Why didn’t Mackas or Peterson indices predict the low 2009 return?o Did you compare median recruits per spawner against Mackas red and blue years?o PSC report suggested that zooplankton production in 2007 was not anomalouso Can one really determine whether it’s a gradual or step change in productivity?o Can you explain other stock patterns (e.g., West Coast Vancouver Island, Fraser pinks)?