Native Trout Program - Bull Trout (Salvelinus confluentus)
The majority of persistent bull trout populations in the United States exist in the Columbia River basin throughout Oregon, Washington, Idaho, and western Montana. Additional portions of the species range extend into Puget Sound and the Olympic Peninsula in northwest Washington, the Klamath River basin in southern Oregon, and the Jarbridge River basin in southern Idaho and northern Nevada (USFWS 2002, 2004a, 2004b). The species range also extends into British Columbia in the Columbia River basin, into Alberta in the Saskatchewan River basin and as far north as the Northwest Territories in the Mackenzie River basin (Reist et al. 2002).
The bull trout was listed as threatened under the Endangered Species Act on November 1, 1999 (64 FR 58910). Previously, the Columbia River distinct population segment of bull trout had been listed as threatened since June 10, 1998. Factors contributing to the listing of bull trout include rangewide declines in distribution, abundance and habitat quality. Land and water uses that alter or disrupt habitat requirements of bull trout can threaten the persistence of the species. Examples of such activities include: water diversions, dams, timber extraction, mining, grazing, agriculture, nonnative fish competition and/or hybridization, poaching, past fish eradication projects, and channelization of streams. These threats are prevalent throughout the Columbia River basin (USFWS 2000, 2002).
The Native Trout Program is conducting projects on bull trout in impacted areas of the Columbia River basin with the overarching goal of providing information toward recovery efforts at a rangewide level. Work occurring in the Imnaha River subbasin in northeastern Oregon is focusing on resident populations of bull trout in headwater streams that have potentially been isolated for over a century to answer questions about effective population size. Work occurring in the Lewis River subbasin in southwestern Washington is investigating the utility of habitat patch analysis to provide initial direction for on-the-ground efforts to determine distribution and abundance of bull trout. An additional project involves the analysis and comparison of various hard parts in an effort to accurately age bull trout.
Reist, J.D., G. Low, J.D. Johnson, and D. McDowell. 2002. Range extension of bull trout, Salvelinus confluentus, to the central Northwest Territories, with notes on identification and distribution of dolly varden, Salvelinus malma, in the western Canadian arctic. Arctic 55:70-76.
USFWS. 2000. Biological Opinion: effects to listed species from operations of the Federal Columbia River Power System. US Fish and Wildlife Service, Regions 1 (Portland, Oregon) and 6 (Denver, Colorado).
USFWS. 2002. Bull trout (Salvelinus confluentus) draft recovery plan. Region 1, US Fish and Wildlife Service, Portland, Oregon.
USFWS. 2004a. Draft recovery plan for the Coastal-Puget Sound distinct population segment of bull trout (Salvelinus confluentus). Region 1, US Fish and Wildlife Service, Portland, Oregon.
USFWS. 2004b. Draft recovery plan for the Jarbridge River distinct population segment of bull trout (Salvelinus confluentus). Region 1, US Fish and Wildlife Service, Portland, Oregon.