An invasion of smallmouth bass from the Great Lakes region is spreading to new areas of the Colorado River in Arizona. The bass have already thwarted efforts to save threatened native fish in the upper river basin, and wildlife officials are fighting to keep the same from happening below Lake Powell, even if it requires cranes, excavators and maybe one day, a giant metal curtain. Federal officials say they took a major step in fighting the bass invasion below the Glen Canyon Dam in June. The National Park Service and Bureau of Reclamation have cleared out a warm backwater in the river where bass and other invasive species used to spawn, eliminating a critical resource for the predatory fish that could wipe out one of the last holdouts for some of the Colorado River’s threatened and endangered fish. Every bass that spawned in the slough became a threat to native fish, experts say. Smallmouth bass eat native fish eggs and young. 

Other invasive species news:

• Summit Daily (Colo.): Colorado Parks and Wildlife makes new invasive zebra mussel veliger discovery in Colorado River 
• KREX (Grand Junction, Colo.): Zebra mussel veliger found in Colorado River near New Castle