YELLOWSTONE NATIONAL PARK, Wyo. (AP) – A stretch of the Gibbon River and its headwater lakes are being poisoned so Yellowstone National Park can remove non-native fish and create a refuge for west slope cutthroat trout and river-running grayling.
The two species, both native to the larger Madison River drainage in the park, are being reintroduced as part of the effort to help flora and fauna of Yellowstone adapt to the warming climate, Senior Fisheries Biologist Todd Koel said.
Warm water in the height of summer closes down waters to fishing on the 8,000-foot Yellowstone plateau with some regularity.
“We look at this as being some of the best habitat that remains for sure in the park, but really in the region, to ensure that west slope cutthroat trout persist in the Greater Yellowstone Ecosystem,” Koel told the Jackson Hole News & Guide.
The Gibbon River is considered a good candidate to support native cutthroat trout and grayling without competition from non-native brook and rainbow trout because of the natural barrier at Gibbon Falls.
West slope cutthroat trout were extirpated from all of Yellowstone except for a tiny stretch of a Grayling Creek tributary called Last Chance Creek. They’ve since been reintroduced into Grayling Creek, parts of Specimen Creek and Goose Lake, and the plan is to return the native cutthroat to Cougar Creek in the future.
Switching the Gibbon River from a haven for exotic to native trout begins with releasing rotenone, a fish poison, in Grebe, Wolf and Ice lakes and 18 miles of stream and river above Virginia Cascades. That work kicked off this month and will continue through the end of September.
Trails and campsites within the upper Gibbon drainage will be closed, including Ice Lake from Aug. 21 to Sept. 30 and the Grebe and Wolf lake area from Sept. 5 to 30.
The project will treat 18 miles of stream and 232 acres of standing water.
Historically, the only fish found in the Gibbon drainage above the falls were mottled sculpin. That changed in 1889, when Yellowstone rangers released rainbow trout in one of the first non-native fish introductions in park history, Koel said. Brook trout were later added to the system.
Rainbows are a particular threat to cutthroat because they readily interbreed, tainting the gene pool.
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