South Fork of the Snake River

The South Fork of the Snake River contains large populations of trout and is considered a world class fishery. Recently, however, the native Yellowstone cutthroat trout population has declined and is now outnumbered by introduced rainbow trout and cutthroat trout/rainbow trout hybrids. The Idaho Department of Fish and Game has changed fishing regulations to protect remaining cutthroat trout through a catch-and-release only policy for cutthroat trout and the encouragement to harvest of all rainbow trout and hybrid trout.








The South Fork Snake River represents one of the last large river habitats where native Yellowstone cutthroat trout remain.

Yellowstone cutthroat trout


Hybrid trout

Rainbow trout



 In the section of river between Pine Creek and Rainey Creek, a few pure Yellowstone cutthroat trout were found, however the majority of the trout we collected were rainbow trout or hybrid trout. In addition to the fishing regulations enacted to reduce rainbow trout and hybrid trout, other researchers are working with agencies in charge of controlling dams for irrigation and hydropower to create more natural flow regimes in the South Fork of the Snake River which may benefit pure Yellowstone cutthroat trout populations.