The Yellowstone cutthroat trout invaded on horseback.
A century ago Glacier National Park officials sought to attract hikers to the remote Camas Creek valley by stocking its barren upper lakes with non-native gamefish. Now they want to turn that drainage into a stronghold for more local fish: the imperiled westslope and bull trout.
A project expected to start this fall would borrow from the experience of Montana’s Department of Fish, Wildlife & Parks restructuring similar lakes in wilderness areas just south of Glacier Park. Barring delays such as loons or black swifts raising young there, federal and state biologists plan to kill all the non-native trout in two upper lakes in the shadow of Heaven’s Peak this September.
“Some people don't often think it, but fish behave differently depending on species,” Glacier spokeswoman Lauren Alley said. “Native cutthroat trout, for example, are easier for eagles and bears to catch because they live closer to the water's surface. They contribute to that larger food web that those wildlife rely on that we often think of when we picture Glacier. A decrease in these native fish species can have far-reaching impacts on some of the animals that are most visible in and iconic of our national parks.”
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The westslope cutthroat used to be the most abundantly distributed trout subspecies in the West, according to U.S. Geological Survey biologist Clint Muhlfeld. Today it only occupies about 30% of its historical Montana habitat. And populations free of hybridization with rainbows or other non-natives is just 3%.
Montana Fish, Wildlife & Parks biologists spent 10 years restructuring the fish populations in 21 lakes of the South Fork of the Flathead River drainage in the Bob Marshall Wilderness Complex and Jewel Basin Hiking Area. FWP Science Program supervisor Matt Boyer said his crews relied on “genetic swamping” in some lakes that had small levels of hybridization, where lots of true cutthroats are stocked to overwhelm the gene pool of mixed-breeds. Other lakes had to be cleared out of fish entirely and restocked with westslope cutthroats and other native species like sculpin.
The Swan Crest work also created a bank of fish populations in high-elevation lakes that should hold clean, cold water far into the future, even as climate change makes more routine habitat too warm for trout. Moyer said the Glacier project would add to that inventory.
“Now we have secure native westslope in these habitats,” Moyer said. “Should we need to go back in the future for genetic conservation reasons we have the ability to do that.”
Glacier plans to use rotenone to kill the Yellowstone cutthroat trout in the upper Camas Creek drainage. In their place park biologists will stock Lake Evangeline and Camas Lake with native westslope cutthroat trout, bull trout and sculpins. Westslope cutthroats are a “species of concern” in Montana, while bull trout have earned federal Endangered Species Act protection as a threatened species.
Those two lakes were stocked by trains of packhorses with non-native trout in the 1920s and ‘30s. In addition, non-native lake trout coming up the North Fork of the Flathead River have nearly eliminated the population of native bull trout in nine of the 17 park lakes that used to be their strongholds, including Rogers.
“Establishing a secure bull trout population at Lake Evangeline and Camas Lake would compensate for the risks to the Rogers Lake bull trout population, help mitigate some of the losses in bull trout abundance in other areas of the park, and expand the overall distribution of bull trout on the west side of the park,” according to Glacier’s project environmental assessment. “The stressors to westslope cutthroat trout and bull trout from non-native fish are compounded by habitat changes that are occurring as a result of climate change, such as altered participation patterns, higher water temperatures and damage to spawning beds from flood events.”
A waterfall above Rogers keeps the lakers (and any other native fish) from getting farther up the Camas drainage. The park does not plan to clear Trout and Arrow lakes, which are below another fish-proof waterfall from the upper basin. But removing the Yellowstone cutts from the upper lakes will help the native westslope cutts in those middle lakes stay genetically pure.
The new cutthroats would come from captures in Avalanche Lake as well as Ford and Starvation creeks in the park’s northwest corner. The bulls would come from Trout and Arrow lakes. The plan calls for capture by trapping or electrofishing, followed by breeding and raising the fish in hatcheries for two years. Then they’ll be returned by helicopter or pack stock to Camas and Evangeline lakes. Some fish might also be reared and raised in streamside incubators.
Despite sitting just over Howe Ridge from Lake McDonald and all its tourist activity the Camus drainage gets relatively little backcountry traffic. Between 2014 and 2018 the Camas Lake campground averaged 52 visitors each August, while 94 stayed at Arrow. That represented about 1.2 percent of Glacier Park’s August backcountry overnight use.
“In addition to the important role that native fish play in our ecosystem, species like the westslope cutthroat are also a part of what make this place special for people,” Alley said. “Anglers love to catch and release them, and it’s exciting to have a fish in our lakes and rivers that has evolved and adapted uniquely to this place.”