Why scientists are removing trout from Klamath mountain lakes

Trinity Alps Subalpine Lake is one nine targeted high elevation lakes targeted for fish removal by the Klamath Mountains Amphibian Habitat Restoration Project to help save the habitat of amphibians.(Photo courtesy of Justin Garwood )

California scientists are removing nonnative trout from selected high-elevation lakes in the Klamath Mountains to restore habitat for native frogs and salamanders.

The lakes were historically fishless before trout were introduced for recreational fishing. Removing those predators could help species such as the Cascades frog and long-toed salamander recover.

Justin Garwood, an environmental scientist with the California Department of Fish and Wildlife, said introduced trout transformed the lakes into ecosystems dominated by fish predators.

“Currently we use mechanical methods,” Garwood said. “We capture fish with gill nets to remove them.”

The Cascades frog in one of the vulnerable amphibian species scientists at the California Department of Fish and Wildlife hope to preserve by removing predatory fish from nine targeted high-elevation lakes where the frogs reside. (Photo courtesy of Justin Garwood )

After catching and killing the fish, crews sink the carcasses into the lakes to return their nutrients to the ecosystem.

“We basically sink the fish into the lake after we remove and dispatch them, and then those nutrients are used to help restart that ecosystem with native fauna starting at the very bottom of the food chain,” Garwood said.

Non-native Brook trout are being removed from targeted high-elevation lakes in the Klamath Mountains to restore the habitat favorable to amphibians.(Photo courtesy of Justin Garwood )

The project focuses on lakes with strong potential for amphibian habitat restoration while preserving popular trout fisheries for anglers.

Garwood said teams are already seeing increases in aquatic insects.

“All of the macroinvertebrates in these lakes, the populations are exploding,” Garwood said.

The goal is to restore conditions that will allow native amphibian populations to recover over time.

An adult long-toed salamander is one of the species California Fish and Wildlife scientists seek to save by removing predatory fish from nine high-elevation lakes where the salamander resides. (Photo courtesy of Justin Garwood ) Guest

• Justin Garwood, environmental scientist and aquatic species coordinator of high mountain lakes with the California Department of Fish and Wildlife