Bull Trout
Pacific Region  


Bull Trout Photo by Bart Gamett
Stillwater River, Montana. Photo by Wade Frendenberg, U.S. Fish and Wildlife Service.
Bull Trout. Photo by Wade Fredenberg, U.S. Fish and Wildlife Service


Bull Trout (Salvelinus confluentus)

Bull trout are a cold-water fish of relatively pristine stream and lake habitats in western North America.  They are protected under the Endangered Species Act.

There was a time when bull trout, like most salmonids, were wildly abundant in the six western states of Oregon, Washington, California, Nevada, Idaho and Montana.

Bull trout were once found in about 60 percent of the Columbia River Basin, but today, they occur in less than half of their historic range, with scattered populations in portions of Oregon, Washington, Nevada, Idaho and Montana. In the Klamath River Basin, bull trout occur in 21 percent of their historic range. They no longer exist in California.
Found to be in peril by the U.S. Fish and Wildlife Service, bull trout were listed as a threatened species throughout their range in 1999.

Bull trout are a cold-water fish of relatively pristine stream and lake habitats in western North America. They are grouped with the char, within the salmonid family of fish.

They have the most specific habitat requirements of salmonids, including the "Four C's": Cold, Clean, Complex and Connected habitat.

• Bull trout require colder water temperature than most salmonids.
• They require the cleanest stream substrates for spawning and rearing.
• They need complex habitats, including streams with riffles and deep pools, undercut banks and lots of large logs.
• They also rely on river, lake and ocean habitats that connect to headwater streams for annual spawning and feeding migrations.

Bull trout are primarily threatened by habitat degradation and fragmentation, blockage of migratory corridors, poor water quality, the effects of climate change and past fisheries management practices, including the introduction of non-native species such as brown, lake and brook trout.

Bull trout decline can be contributed to human activities such as development, logging and agriculture that have degraded its habitat.

Of all salmonids, bull trout are excellent indicators of water quality. Today, water quantity has decreased, water quality has diminished, and introduced, non-native fish like brook and lake trout have competed with bull trout for their native habitat.

Protecting and restoring bull trout habitat improves the water quality of rivers and lakes throughout the west. When habitat is improved, bull trout have a greater chance of recovery.

Last updated: October 12, 2010