ABSTRACT
This chapter explores the interactive effects of anthropogenic trends and climate cycles on salmon declines in the Columbia and Snake river basins. A basic population model—including anthropogenic and environmental factors—is discussed, and literature relating decadal-scale climate patterns and the response of the North Pacific ecosystem is reviewed. From this background a ratchet-like decline in Columbia and Snake river salmon production has resulted from the interactions of human activities and climatic regime shifts. These interactions are illustrated using hundred-year patterns in spring chinook salmon Oncorhynchus tshawytscha catch, the Columbia River hydroelectric generating capacity, and a climate index characterizing the shifts between a cool/wet regime favorable to salmon and a warm/dry regime unfavorable to salmon. A half-century correlation of the climate index and chinook catch suggests that a favorable climate regime counteracted detrimental impacts of hydrosystem development between 1945 and 1977, while an unfavorable climate regime negated beneficial effects of salmon mitigation efforts after 1977. This hypothesis is elaborated by a comparison of changes in the climate index relative to changes in Snake River salmon survival indicators. Proposed Snake River salmon restoration plans are considered in terms of this counteractive effects hypothesis. The recent declines of salmon stocks have led a number of groups to propose plans that discontinue the present recovery actions, especially transportation of juvenile salmon around the dams. This chapter hypothesizes that salmon recovery efforts, in part, have been limited by recent poor climate/ocean conditions. If this hypothesis is true, then eliminating the transportation program could be detrimental to fish. If the hypothesis is false, then eliminating transportation may be a viable recovery measure. In either case resolving the issue of counteracting processes is essential prior to making major changes to hydrosystem operations. In a larger perspective the influence of climate cycles on the Columbia River illustrates that in achieving sustainability we do not achieve stability. The better we understand that stocks will fluctuate by factors outside our control, the better chance we have to avoid the ratchet-to-extinction—and this is the first goal of sustainability.
