Dillon Field Office Helps Restore Westslope Cutthroat Trout in Multiple Southwest Montana streams

Story by: Alden Shallcross, State Lead - Montana/Dakotas Aquatic Habitat Management Program 

Westslope Cutthroat Trout (WCT) play a fundamental role in the regional ecosystem dynamics and can offer excellent recreational opportunities for sportsman. Their historical range included all of Montana west of the Continental Divide, as well as the upper Missouri River drainage.  

Unfortunately, WCT populations have been seriously reduced by hybridization with Rainbow and/or Yellowstone Cutthroat Trout, as well as habitat loss and degradation. In fact, the state has listed them as a Montana Fish of Special Concern that is vulnerable to extirpation due to very limited and/or potentially declining population numbers, range and/or habitat.  

To assist with the maintenance and restoration of this important native fish, the Western District routinely coordinates with partners to implement projects that benefit the species. In 2020, this included the following restoration efforts by the Dillon Field Office’s fish biologist:  

Ramshorn Creek Ramshorn Creek is in the Tobacco Root Mountains, northeast of the Dillon Field Office. This is a cooperative project between the State of Montana, BLM, Forest Service, and private landowners that encompasses about nine miles of historic habitat.  

In 2019, the drainage was chemically treated with rotenone to remove nonnative salmonids. In 2020, a sampling using eDNA indicated that a few scattered fish remained in the drainage. To completely remove nonnative and hybridized trout, a rotenone treatment was conducted again in August 2020 to target remaining salmonids. 

Meadow Creek Meadow Creek contains one of the two remaining pure WCT populations in the Big Sheep Drainage. The associated fish were used in 2019 for the Greenhorn WCT restoration project and are a strategic source of brood stock for future projects in adjacent drainages. A fish barrier (Photo 7) was constructed on BLM in early fall 2020 to prevent inter-breeding with non-native species found lower in the watershed. This project will protect about five miles of occupied habitat and ensure the genetic purity of brood stock for future restoration efforts.  

French Creek In 2017, BLM contributed funding to construct a fish barrier (Photo 8) in support of a native westslope cutthroat restoration project in the French Creek drainage in southwestern Montana. The fish barrier was completed in 2019. In 2020, a multi-agency cooperative effort chemically treated more than 40 miles of historic westslope habitat. In 2021, the drainage will be re-treated to address any remaining salmonids. When completed, native westslope cutthroat trout and arctic grayling will be re-introduced into the project area.