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Cutthroat Conservation Project Moving Towards Completion; FWP Proposes to Waive Angling Limits on Koessler Lake within the Bob Marshall Wilderness Area

Fishing - Region 1

Monday, June 30, 2014

Project status: The South Fork Flathead Cutthroat Conservation Project has been systematically removing non-native fish and replacing them with pure westslope cutthroat. The goal has been to maintain the world class genetically pure westslope cutthroat fishery in the South Fork Flathead River Drainage. FWP Project Biologist Matt Boyer reports that 12 mountain lakes have been successfully chemically treated and an additional 6 lakes are being genetically swamped and may not require chemical treatment. Only three lakes remain on the original list of 21 encompassed by the project in the South Fork Flathead Drainage.

This year’s activities and limit waiver: This year, Koessler Lake is scheduled for rotenone treatment in September. Koessler is an 86 acre lake located at the head of the Gordon Creek drainage within the Bob Marshall Wilderness Area. The lake was historically stocked with nonnative Yellowstone cutthroat trout and presently contains westslope cutthroat/Yellowstone cutthroat trout hybrids. Koessler is a remote backcountry angling destination. In past years, anglers have asked for limit waivers to allow more harvest of fish prior to treatment. The current bag limit is 3 trout per day. The proposal to lift the fishing bag limit on Koessler Lake will be submitted to the Montana Fish, Wildlife & Parks Commission. The FWP Commission will evaluate public comments and consider final approval of this proposal at their July meeting. It would go into effect immediately upon approval. Please contact your local Fish and Wildlife Commissioner if you have comments; address comments to:

Project accomplishments: In 2007, FWP initiated the South Fork Flathead Cutthroat Conservation Plan with the goal of removing headwater sources of nonnative introduced trout in 21 lakes to protect the existing genetically pure westslope cutthroat trout populations in the drainage. Replacement involves either chemical treatment or genetic swamping (heavy stocking of pure westslope cutthroat to dilute the nonnative genes). To date, swamping or chemical treatment has been used to restore native westslope cutthroat trout in 18 of the 21 lakes. Lakes are restocked the following summer after treatment to restore recreational fishing. Only Koessler (this year), Handkerchief (2015), and Sunburst (2016) lakes remain to be treated with rotenone and restocked with native westslope cutthroat.

Funding from Bonneville Power Administration, collaboration with the US Forest Service, and public support from groups such as Backcountry Horsemen and Trout Unlimited has been absolutely critical to the success of this work and underscores the importance of maintaining this native fishery.

“Not only are westslope cutthroat a prized sport fish, they are a key component of Montana’s natural heritage and its aquatic ecosystems,” says Boyer. “Conservation of this fish is important on many fronts.”

Boyer notes that a great deal of effort has gone into this project over the past seven years. He notes a few relevant stats:

  • FWP has conducted hundreds of amphibian, plankton, and aquatic insect surveys to document species composition and population recovery after rotenone treatment. These are the components of the aquatic food web important for ecosystem health, and in part a measure of the success of the project.
  • Since 2007, over 11,000 miles of trail have been hiked or ridden on horseback while conducting pre- and post-treatment surveys, rotenone treatments, and collecting wild fish to develop local source stocks of westslope to repopulate these lakes.
  • Almost half a million westslope cutthroat have been stocked in the lakes involved in the cutthroat conservation project.

Boyer is encouraged by the project accomplishments. “The gains that have been made for westslope cutthroat trout and the South Fork Flathead fishery are a tremendous benefit for the resource,” Boyer said. “The partnerships made along the way will pave the way for more conservation successes into the future.”

For more information on this project, visit FWP Region One’s website.

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