Yellowstone park has lake trout on the run
By Mike Koshmrl, Jackson Hole, Wyoming
November 12, 2012
More than 300,000 lake trout were caught in Yellowstone Lake and killed this year, a record for fisheries managers trying to suppress the invasive species.
The netting has been going on since 2000 as part of an effort to restore decimated populations of native cutthroat trout in the national park’s largest lake.
The culling operation is finally reaching kill levels necessary to effectively suppress the ecologically damaging lake trout population, estimated at about 500,000 adult fish. Some 224,000 lakers were netted in 2011, but the total kill for the decade before was just 500,000.
“We had a banner year for a couple of different reasons,” Yellowstone spokesman Dan Hottle said. “Number one is we’re using the tracking telemetry to find out where the fish were spawning and where they’re congregating.”
The kill was also successful this year because fishermen fished as long as they could, netting the 139-square-mile lake from just after the ice melted until last week, Hottle said. In 2011, Yellowstone contractors netted the lake for 17 weeks, but the season spanned just 10 weeks in 2010 and three weeks in 2009, he said.
The big lakers, also known as mackinaw, have outcompeted and eaten the native cutthroats since they were illegally introduced into Yellowstone Lake.
Fishermen employ two methods to catch and kill mackinaw on Yellowstone Lake: trap nets and gill nets.
In gill netting, a method that kills most of the fish, the cutthroat catch was up this year to about eight per 100 lake trout. Most years, it’s closer to four cutthroat per 100 lake trout.
Monitoring also indicated the number of juvenile cutthroat is increasing.
Cutthroat trout are considered a keystone species in the Yellowstone Lake ecosystem. They historically ran up 60 feeder streams by the thousands each spring to spawn. The spawn made them an easy catch for predators, and cut-throat were once an important food source for grizzly bears, bald eagles, ospreys and river otters.
Restoration efforts for cutthroat on Yellowstone Lake are supported by volunteers and by financial contributions from the Yellowstone Park Foundation, Trout Unlimited, Greater Yellowstone Coalition and the National Parks Conservation Association.
Yellowstone officials are satisfied with the intensity of the lake trout kill and plan to hold netting at current levels into the near future, Hottle said.
“I think we’re about as ramped as we can get right now,” he said. “As far as I know, we don’t have any plans to bring on any additional boats.”