Weak Salmon Run Closes Some Northwest Fisheries
May 19, 2005 -- Idaho, Oregon, and Washington have ended commercial fishing in the Columbia River after this year's salmon run fell drastically short of expectation. Fisheries experts had expected 254,000 chinook salmon would pass the Bonneville Dam during the annual run, but only 52,000 have passed the dam.
Officials are having difficulty explaining the low numbers. Changes in the climate, unexplained problems with the salmon spawn, predators, and the hydroelectric power plants along the river have all been suggested as possible factors.
A National Research Council report, Managing the Columbia River: Instream Flows, Water Withdrawals, and Salmon Survival, discusses changes that have affected salmon, including increasing water temperatures, river flow velocities and predation rates. Large salmon returns between 2001 and 2003 were considered by many to be the result of favorable ocean conditions, but the report notes that many variables make it difficult to explain precisely the numbers of salmon that return to the mouth of the Columbia River.
Another report, Upstream: Salmon and Society in the Pacific Northwest, explains in detail the adverse effects of dams and other human activities on salmon in the Columbia, and how changes in ocean conditions and climate influence these fish populations, as well. The report also looks at the impact of hatcheries, introduced to mitigate the problems caused by dams but which have actually had population, ecological, and genetic effects on wild salmon stocks.