Lake trout have been a presence in Yellowstone Lake since the 1990s, when someone had the misguided notion that it would be a good idea to stock the lake with them. But lake trout don’t coexist well with the smaller cutthroat trout, natives of Yellowstone Lake: they eat them and displace them from prime areas.
At their peak, there were 4 million cutthroat trout in Yellowstone Lake, according figures compiled by Trout Unlimited. Today there’s far less, and that’s having a ripple effect on the Greater Yellowstone Ecosystem. Lake trout are deep-water trout who never leave the lake; cutthroat, on the other hand, swim up tributaries for spawning and whatnot, making them prime targets for bear, osprey, otters pelicans and other fish eaters. Fewer cutthroats mean fewer predators, and that upsets the balance of Yellowstone.
The National Park Service has taken some efforts to rid Yellowstone Lake of lake trout, most notably with gill-netting in deep waters. This season there will be 10 weeks of commercial gill-netting, and NPS employees also gill-net, taking out 35,000 lake trout so far this summer.
Trout Unlimited officials say that’s not enough: they’d like to see the season run all the way into mid-October, and they’d like to see another commercial fisherman allowed on the lake. But more is needed, they say: they’d like to see Clear Creek reopened for cutthroat spawning, and they’d like research done to find lake-trout spawning beds so they can be destroyed. But that’s a labor-intensive effort that includes radio transmitters, and at a time when budgets are tight, there may not be room in the NPS spreadsheets for this sort of endeavor. We’d guess some sort of private fundraising will be needed before large-scale efforts can be made to rid Yellowstone Lake of lake trout.
Photo of lake trout courtesy of National Park Service.