Non-native trout will be killed off in Montana lakes

KALISPELL – A 10-year plan to remove hybrid and nonnative trout from 21 lakes in and around the Bob Marshall Wilderness to make way for native westslope cutthroat trout is scheduled to begin this week.

State Fish, Wildlife and Parks officials plan to start Tuesday by poisoning hybrid trout in Black Lake in the Jewel Basin Hiking Area. Biologists are to follow at Blackfoot Lake on Oct. 2.

The toxin attacks trout gills, leaving other aquatic life unharmed.

Each of the 21 lakes to be poisoned is home to hybrid fish, genetic crossbreeds mixing the genes of native westslope cutthroat trout with nonresident Yellowstone cutthroats and rainbows.

Each of the waterways also feeds into the South Fork Flathead River, a place state biologists call “the major stronghold of westslope cutthroat trout within its native range.”

That range now is reduced to just 9 percent of its historic area, making the South Fork an increasingly important native fishery.

In some places, non-natives and hybrids have completely eliminated the westslopes.

Anglers who enjoy fishing the lakes and wilderness advocates opposed to toxins in the backcountry both raised concerns as the plan was being formed over the past four years. Some argued that the airplanes and boats needed to apply the toxins have no place in wilderness, where motorized vehicles are prohibited.

The poisons break down and dissipate quickly, officials said.

The project involves several agencies. The Bonneville Power Administration is paying for the work as part of its mitigation for habitat lost behind Hungry Horse Dam; the Forest Service is involved because many of the lakes are on federal forests; and the state FWP is implementing the plan.

Once trout in the lakes are killed, FWP officials said, biologists will restock them with genetically pure westslope cutthroats in time for next year’s fishing season.

The project starting next week spans a full decade at a cost of several hundred thousand dollars per year. Eleven of the targeted lakes are in the Bob Marshall, eight are in the Jewel Basin and a couple are on nearby forest lands.

FWP officials maintain the work is important if they are to avoid the even greater restrictions and costs that would be incurred if westslope cutthroat trout were listed for protection under the Endangered Species Act.