Tuesday, June 28, 2011

Bull Trout Restoration

bull trout      (photo credit: USFWS)

As part of an overall recovery strategy for bull trout, the U.S. Fish and Wildlife Service and the Oregon Department of Fish and Wildlife will reintroduce the species to the Clackamas River, a major tributary of the Willamette River.

Beginning in the summer of 2011, bull trout of different life stages will be reintroduced into historic bull trout habitat in the upper Clackamas River, within the Mt. Hood National Forest.

The project is expected to include additional fish transfers annually for at least seven and possibly up to 15 years.  The goal is to reestablish a self-sustaining population of 300-500 spawning adult bull trout within 20 years.

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

Bull trout have been extirpated from four sub-basins in the Willamette River Basin, including the Clackamas River. Once widely distributed in the Clackamas River, the last known bull trout was documented there in 1963.  The species is highly unlikely to re-colonize the area naturally due to the geographic distance to existing bull trout populations.

Once plentiful throughout the coldwater rivers and lakes of the Northwest, bull trout populations in the U.S. are now scattered and patchy in portions of Oregon, Washington, Idaho, Montana, and Nevada.

Bull trout occur in the Columbia and Snake River Basins, extending east to headwater streams in Montana and Idaho and north into Canada, and south into the Klamath River Basin in south-central Oregon.  Though still wide-ranging, many of the remaining populations are small and isolated from each other.

Some bull trout populations are migratory, spending portions of their life cycle in larger rivers or lakes before returning to smaller streams to spawn, while others complete their entire life cycle in the same stream. Some bull trout in the Coastal-Puget Sound population migrate between fresh- and saltwater.

Bull trout require extremely cold, clean water and specific habitat features, as well as connectivity from river, lake, and ocean habitats to headwater streams for annual spawning and feeding migrations.

source: U.S. Fish and Wildlife Service

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