Bull Trout
Bull trout video Oct. 2010
In the Columbia River Basin, bull trout historically were found in about 60 percent of the Basin. They now occur in less than half of their historic range, primarily in upper tributary streams and several lake and reservoir systems. Bull trout also occur in the Klamath River Basin, the McCloud River in California and in coastal watersheds in Canada, Oregon and Washington.
Bull trout are more sensitive to increased water temperatures, poor water quality, and low flow conditions than many other salmonids. They require especially clean, cold water, and temperatures above 59 ºF are thought to limit the survival of juveniles.
Bull trout have declined due to habitat degradation and fragmentation, blockage of migratory corridors, poor water quality, past fisheries management, and the introduction of non-native species such as brown, lake and brook trout. While bull trout occur over a large area, their distribution and abundance has declined and several local extinctions have been documented. Many of the remaining populations are small and isolated from each other, making them more susceptible to local extinctions.
Expected global climate change threatens bull trout throughout their range. With a warming climate, cool-enough spawning and rearing areas are expected to shrink during warm seasons, in some cases very dramatically, causing them to become even more isolated from one another. Climate change will likely interact with other stressors, such as habitat loss and fragmentation, invasions of non-native fish, disease and other threats, to render some current spawning, rearing and migratory habitats marginal or wholly unsuitable.
Declines in bull trout populations prompted the U.S. Fish and Wildlife Service to list Columbia River bull trout as threatened under the Endangered Species Act in 1998 and more comprehensive coterminous U.S. listing designation occurred in 1999.
Bull trout critical habitat designation Sept. 2010
More information on USFWS draft bull trout recovery plans
Bull trout fact sheet