Native fish project down to three headwaters lakes

Three of 21 wilderness lakes in a project to restore native cutthroat trout to the headwaters of the South Fork of the Flathead River remain to be treated and stocked.

Work on the South Fork Flathead Cutthroat Conservation Project began in 2007. Since then, 12 lakes have been treated with chemicals and then restocked, and six more have been “swamped” with high numbers of genetically pure trout.

Now Montana Fish, Wildlife and Parks is proposing to waive angling limits on Koessler Lake, an 86-acre lake at the head of Gordon Creek in the Bob Marshall Wilderness. The lake is scheduled to be treated with rotenone this September to purge its existing fish population so the lake can be restocked with genetically pure westslope cutthroats.

The South Fork of the Flathead is considered a stronghold for westslope cutthroats, a fish that has been in decline in other Montana waters. The Hungry Horse Dam has acted as a barrier to movement of lake trout upstream from the rest of the Flathead River system, but nonnative trout long ago planted in the wilderness area threaten the existence of genetically pure westslope cutthroat trout.

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

The project is funded by the Bonneville Power Administration as mitigation for impacts from the Hungry Horse Reservoir. The Forest Service, Back Country Horsemen of the Flathead, Trout Unlimited and other groups were key partners in the project.

Boyer said he’s encouraged by the project’s accomplishments. FWP biologists have conducted hundreds of amphibian, plankton and aquatic insect surveys to document species composition and population recoveries after rotenone treatments.

More than 11,000 miles of trail were covered on horseback or foot to conduct the surveys, to carry out rotenone treatments and to collect fish to develop source stocks for repopulating the lakes.

Nearly half a million westslope cutthroats have been stocked in the headwaters lakes after they’ve been treated. Boyer said fishery population recoveries have been rapid, one of the project’s major goals.

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

Koessler Lake, a remote backcountry angling destination, was historically stocked with nonnative Yellowstone cutthroat trout and presently contains westslope cutthroat/Yellowstone cutthroat trout hybrids.

Anglers have asked for limit waivers to allow more harvest of fish in lakes slated for treatment.

The proposal to lift the current three-trout-per-day bag limit will be submitted to the Montana Fish, Wildlife & Parks Commission for their July meeting.

The waiver would go into effect immediately upon approval. Public comments to on the proposal can be e-mailed to fwpcomm@mt.gov.