Fishing - Lake trout

Damage caused by lake trout in Yellowstone Lake is enormous to the ecological balance of the region.

  • Lake trout feed on cutthroat trout and compete with all the native fish for the same food sources.
  • Cutthroat trout play an important part in the Great Yellowstone Ecosystem.
  • Park personnel, the Wyoming Game and Fish, the U.S. Fish and Wildlife Service and anglers all work to control the lake trout population.

Lake Trout versus Cutthroat Trout
The genetic purity of Yellowstone Lake cutthroat trout makes them extremely valuable; however, the population has been exposed to nonnative lake trout. In the mid-1980s, lake trout were moved illegally from Lewis Lake to Yellowstone Lake where they consume native cutthroat trout. The declining number of cutthroat trout that return to Yellowstone Lake tributaries to spawn in the spring suggests that cutthroat trout abundance in the lake has declined to an extremely low level.

The potential damage a lake trout population can cause cutthroat is enormous. A lake trout may live for 25-40 years, a cutthroat, maybe 10 years. Typically, a mature lake trout will eat 50 cutthroats a year. The non-native lake trout are not only eating several cutthroats a year, but they compete with the native fish for the same food sources.

Ecological and Economical Impact
Yellowstone National Park places a high priority on preservation and recovery of this cutthroat trout population because of its importance in maintaining the integrity of the Greater Yellowstone Ecosystem. Cutthroat trout live and spawn in shallow streams and waters, providing prey for many species of birds and mammals. Grizzly bears, otters, eagles, white pelicans and osprey are just a handful of the animals that stand to lose a valuable food source if the Yellowstone Lake population is diminished.

Furthermore, the cutthroat trout in the lake help generate millions in revenues resulting from the excellent sport fishing found in Yellowstone and surrounding communities. Anglers come from all over the world to fish for these native wild fish.

Removal Efforts
Efforts to remove lake trout from Yellowstone Lake have been ongoing since their presence was first confirmed in 1994. This is an ongoing problem for Park personnel, the Wyoming Game and Fish and the U.S. Fish and Wildlife Service.

The majority of removal efforts in 2007 were control net sets targeted at young lake trout residing at depths typically greater than those occupied by cutthroat trout. Fisheries biologist likens removal of non-native lake trout from Yellowstone Lake to "weed control". To date, more than 80,000 lake trout have been removed.

In recent years, Yellowstone Park has issued a release inviting anglers to help control the lake trout population in Yellowstone Lake by allowing anglers to fish spawning areas of the lake during September and October. Anglers are urged to fill out response cards after fishing the lake to report their catches. This helps fisheries biologists better monitor catch rates.

A Forever Problem
It is unrealistic to think that the last lake trout will ever be caught in Yellowstone Lake. A more realistic goal is to try to get ahead of the problem. This may be possible through the combined efforts of all concerned, including anglers.

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