Westslope Cutthroat Trout and Bull Trout Preservation at Gunsight Lake
Gunsight Lake was historically fishless but stocked in 1916 and 1920-1936 with non-native fish, including rainbow trout, which are able to migrate downstream and hybridize with native westslope cutthroat trout. The lake is well positioned to provide secure habitat for native fish due to downstream waterfalls that block upstream fish migration. Given its high elevation, Gunsight Lake also has a high likelihood of sustaining the cold-water habitat necessary for westslope cutthroat trout and bull trout to persist in a changing climate.
Glacier National Park is proposing to remove non-native rainbow trout from Gunsight Lake using a fish toxicant. Following the removal of the rainbow trout, bull trout and genetically pure westslope cutthroat trout (less than one percent non-native genes) would be translocated into Gunsight Lake.
Chris Downs, Aquatic and Physical Science Programs Leader
In the St. Mary River drainage on the east side of Glacier National Park, native westslope cutthroat trout are at risk from hybridization with non-native fish, and there are multiple threats to bull trout populations throughout the park, including non-native fish. Climate change presents additional threats that could compound these stressors. Westslope cutthroat trout are a state listed species of concern and bull trout are listed as threatened under the 1973 Endangered Species Act.