Lake Trout Removal Working in Yellowstone National Park

There’s less and less lake trout in Yellowstone Lake, thanks to recent removal efforts aimed at restoring cutthroat trout to their historical high.

According to the Cody Enterprise, biologists believe the balance of lake trout to cutthroat trout is now roughly 50-50. Reportedly, the balance was once as severe as 90-10. Cody’s Dave Sweet, a volunteer with Trout Unlimited, told the Enterprise that “the cutthroat population has tripled” over the past four years.

The news itself is not new. Trout Unlimited announced six years ago it intended to restore Yellowstone cutthroat trout to their former glory. Subsequent removal efforts appeared to pay dividends in both 2012 and 2014, with crews reporting a resurgence in cutthroats. Last December, crews reported removing over 300,000 lake trout.

According to the Enterprise, Sweet reported the news at an outdoor writers conference in Billings, adding that removal efforts are far from over. From the Enterprise:

Likewise, Yellowstone National Park Superintendent Dan Wenk said it is too soon to declare any kind of victory.

“I don’t want to get too far ahead of ourselves,” Wenk said. “It’s encouraging.”

Sweet is the Yellowstone Lake special project manager, devoting the last 8 1/2 years to overseeing a possible rebound of the cutthroat whose numbers were tumbling due to this invasive species.

Nobody knows who introduced lake trout to Yellowstone Lake, but the bigger, aggressive lake trout were well on their way to wiping out the native cutthroat that play a significant role in the ecology of the park.

In recent years, the Park Service, aided by donors, has spent $2 million annually to pay hired gillnetters to catch and kill as many lake trout each summer as possible. The figure has topped 300,000 for about three years in a row and by the third week in July this year the number was approaching 200,000.

“It’s the right thing to do,” said Brett Prettyman, intermountain communications director for Trout Unlimited. “We (humans) screwed it up.”

Besides being an attractive species for anglers, the cutthroat’s healthy existence in the Park, swimming around not far beneath the surface, helped feed bears, osprey, eagles and other species.

“Lake trout don’t fill that niche because they’re so deep,” Prettyman said.

Those groups had to seek other food sources.

“It’s truly an ecosystem impact,” Sweet said of the trout’s role. “It’s called a keystone species in Yellowstone. It really ripples through the ecosystem.”

Sweet and Prettyman both stressed that netting alone won’t remove lake trout from Yellowstone Lake. For instance, over the past few years, crews have started catching and attaching telemetry gadgets to the fish; telemetry allows crews to trace lake trout to their spawning beds and remove both fish and fry from them.

Both men added they appreciate lake trout in general, but say Yellowstone cutthroat trout are preferable.