Arizona Game and Fish Department

Humpback chub.

The National Park Service approved a plan Wednesday to protect endangered fish in the Colorado River below Glen Canyon Dam.

The National Park Service will encourage what it's calling "an incentivized harvest" of brown trout, a non-native predator whose population has grown too big. The agency will reward people who catch the fish and support tournaments to remove them from the river.

The Park Service has gone to great lengths to protect native aquatic species including tagging and transporting the humpback chub to nearby tributaries.

After Glen Canyon and other dams were built to provide electricity and water to the Southwest, the water temperature downstream dropped, slowing the chubs' growth. Silt backed up behind the dam so there was no place to hide when non-native predators were introduced to the river. Many native fish died off and the chub became endangered.