Review of the Influence of Climate on Salmon

Evidence suggests that the year-class strength of salmon populations is related to decadal scale climatic/ocean fluctuations. The interactions have complex latitudinal patterns and appear to involve the major food web and current structures of the North Pacific. To understand the effect of climate on Columbia River salmon the North Pacific system must be considered. A brief review of the patterns, the postulated mechanisms and indicators of the patterns follow. In general, two major climate regimes have been identified; one associated with cool and wet climate in the Pacific Northwest and another associated with warm and dry Pacific Northwest weather. The warm/dry regime favors stronger year class strengths of many Alaskan fish stocks while the cool/wet regime favors stocks on the West Coast of the lower United States. Within seasons climate factors related to the timing of the spring winds also have been shown to affect survival.