Biologists in Yellowstone are planning to complete a project to kill off non-native brook and rainbow trout in the upper Gibbon River drainage between Virginia Cascades and Little Gibbon Falls.

They will use rotenone, a naturally occurring toxin derived from the roots of tropical plants. Downstream, they will use potassium permanganate to remove the effects of rotenone.

It's the final phase of the project for that section of river.

Biologists then plan to reintroduce native Arctic grayling and Westslope cutthroat trout. Officials say stocking non-native rainbow and brook trout nearly eliminated grayling and Westslope cutthroat trout from Yellowstone.

In recent years, park officials say, native species have been restored to the East Fork of Specimen Creek, Goose Lake and Grayling Creek.

Impacted fisheries will be closed during the project, but access to the sites may be impacted.

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