Lake Trout Control

Since the presence of lake trout in Yellowstone Lake was confirmed in 1994, intensive gillnetting to remove these invasive fish, coupled with research on their abundance and distribution, has helped target the timing and location of removal efforts to maximize the number of lake trout caught. Park staff have also learned how to minimize bycatch of Yellowstone cutthroat trout, which are vulnerable to gillnets if positioned incorrectly in the lake. The National Park Service now uses a boat designed specifically for gillnetting on Yellowstone Lake.

Most removal efforts are now targeted from May to mid-August at young lake trout that reside in depths greater than those occupied by cutthroat trout. On a typical day during the open water season, more than 15 miles of small mesh are placed on the lake bottom in water 40–65 m deep. The number of lake trout caught per unit of effort (number captured for every 100 meters of net each night) has been creeping upward in recent years. The lake trout are also removed by electrofishing, using a boat loaned to the park each year by the U.S. Fish and Wildlife Service.

Carcasses are returned to the lake each day to ensure that nutrients are not removed from this relatively nutrient-poor system. More than 450,000 lake trout have been removed from Yellowstone Lake since 1994.

Updated 7/23/10