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South Fork Westslope Cutthroat Trout Project

Tough Love Article

"Why it makes sense to kill some fish to save others"

If you have found this site you are probably interested in the world-class westslope cutthroat trout fishery in the South Fork of the Flathead River. The population of westslope cutthroat trout in the South Fork is the strongest and most vibrant in Montana, and perhaps in the entire West.

The information at this site focuses on the Westslope Cutthroat Conservation Project in the South Fork of the Flathead Drainage. The purpose of this program is to protect the genetic purity of westslope cutthroat trout in the South Fork Flathead Drainage by removing hybrid trout from headwater lakes and restocking with genetically pure westslope cutthroat trout. This project seeks to conserve the genetically pure westslope cutthroat population in the South Fork of the Flathead River. When the hybrids are removed, the threat of hybridization to the genetically pure westslope cutthroat in the river will be greatly reduced.

Over a 10-year period, the project will treat up to 21 high mountain lakes in late fall with rotenone or other fish toxicants to remove nonnativetrout and their offspring so they won’t hybridize with westslope cutthroat trout. Rainbow trout and Yellowstone cutthroat trout readily hybridize with native westslope cutthroat and produce fertile hybrids that produce more young. This project is a fishery replacement project, not a fishery removal project. When a fishery is eliminated, a new fishery using genetically pure westslope cutthroat will be quickly re-established. "Swamping" or over-planting genetically pure cutthroat in lakes with hybrids, has seen limited success in some lakes. We will continue to monitor the level of hybridization in the candidate lakes and investigate continued swamping to rehabilitate some lakes without using toxicants.

Thanks for your interest in the conservation of westslope cutthroat trout in the South Fork Drainage!

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