JACKSON, Wyo. (AP) — Biologists are making their first use of electroshock in their efforts to save native cutthroat trout in Yellowstone National Park from another voracious species of trout.

The electroshock treatment is being done to kill off lake trout that have invaded Yellowstone Lake when the unwanted fish is still spawning and in the earliest stages of its life.

Until now, netting of lake trout has been the park's main method of suppression.

But limited electroshocking and dredging being employed this fall target the non-native fish in their spawning beds.

U.S. Geological Survey research biologist Bob Gresswell says efforts overall to reduce the impacts of predatory lake trout on Yellowstone Lake's cutthroat trout are going well but more work needs to be done.