Climate Change and Salmon in the North Pacific - Winners and Losers

Since salmon are key species in North Pacific ecosystems, understanding historical patterns in their abundance, biomass, distribution, growth, and survival can help us anticipate future climate-related changes. Data need to be interpreted based on knowledge of the various life histories, and certain data types are most appropriate for particular scales. Indicators specific to Pink, Chum, ocean-type Chinook, and ocean-type Sockeye Salmon are most relevant to marine environments be­cause these species spend little time in freshwater. Ocean-type Chinook and Coho salmon populations may be most indicative of conditions in coastal regions close to the point of natal stream entry. This presentation focuses on the analysis of commercial catch estimates that are appropriate abundance indices at the scale of major regions of the North Pacific Ocean, and are available for at > 85 yrs. Recent salmon catches have been among the highest on record, with no indication of decline; the 2009 catch was the highest to date. Analyses confirm climate-related shifts in abundance, associated with reported ecosystem regime shifts in approximately 1947, 1977, and 1989, but there is little evidence to support a major shift after 1989. From 1990, generally favourable climate-related marine conditions in the Western North Pacific Ocean, as well as expanding hatchery operations and improving hatchery technologies, are increasing abundances of Chum and Pink Salmon. In the Eastern North Pacific Ocean, climate-related changes are playing a role in increasing Chum and Pink Salmon abundances and declining numbers of Coho and Chinook Salmon. In general, Pink and Chum Salmon appear to be climate winners while Coho and Chinook Salmon are losers; it is not possible to generalise for Sockeye Salmon. To understand climate effects at the scale of regional stock groupings, biological populations and Conservation Units requires investigation of non-catch time series including patterns in size at age (marine and freshwater growth); age at maturity; return timing and changes in migratory behaviour; survival (stock recruitment); and distribution (based on tagging and genetic stud­ies).