Endangered Humpback Chub On Upswing In Colorado River Basin

Jan 21, 2020

An endangered fish found in the Colorado River basin is on the upswing, federal officials said Tuesday as they proposed reclassifying the humpback chub as threatened.

The fish that gets its name from a fleshy bump behind its head is one of four endangered fish that make their home in the Colorado River and its tributaries. It was listed as such in the late 1960s as its numbers fell drastically before stabilizing more than a decade ago.

The largest population now is found at the Grand Canyon, with four, smaller wild populations upstream of Lake Powell in Utah and in Colorado canyons. The U.S. Fish and Wildlife Service said the fish is no longer at the brink of extinction and is better suited as threatened.

"I really think the science supports this decision," said Tom Chart of the U.S. Fish and Wildlife Service. "It's an opportunity to step back and recognize progress from a variety of these collaborative programs that have been working on ecosystem health and endangered species recovery for a long period of time."

The humpback chub likes rocky waterways with swift currents, but it also needs warm and muddy water to spawn. Dams built on the Colorado River and its tributaries have changed the natural flow of the river, challenging the humpback chub along with non-native predators.

Small mouth bass largely are the concern in the Colorado River's upper basin, which includes Utah and Colorado. Rainbow trout feed on the humpback chub in the lower basin.

Those working to recover the fish have removed predators when needed, altered the flow from dams to benefit the humpback chub and installed structures to allow the fish to move between areas.

Not everyone is convinced the fish can continue to thrive in the face of climate change, drought and proposals for new dams, and without significant human intervention.

"All of those things taken together, we think that the fish management going forward warrants precaution, not optimism," said Taylor McKinnon of the Center for Biological Diversity. "This proposal is dangerously optimistic about the fish's future."

Jen Pelz, wild river program director for WildEarth Guardians cited specific infrastructure projects currently proposed in the river's upper and lower basins as reasons not to downlist the fish. 

"There are numerous water development and hydropower projects, including the Lake Powell Pipeline and the two hydropower projects proposed on the Little Colorado (River), that will only further drain the river and destroy critical spawning habitat for the humpback chub," Pelz said in a statement.  

The notice on the proposal to reclassify the fish will be published in the federal register Wednesday, marking the start of a 60-day public comment period. The action was expected after the U.S. Fish and Wildlife Service said almost two years ago that it was considering reclassifying the humpback chub.

The last set of recovery goals, developed in 2002, called for two core populations of at least 2,100 adult humpback chub to consider listing it as threatened. Those exist at the Grand Canyon with 12,000 adult fish and at a second location near the Colorado-Utah border that's much smaller in size.

The fish once had a broader range, but the construction of the Flaming Gorge Dam in Wyoming and Hoover Dam on the Nevada-Arizona border led to two other populations becoming extinct. An eighth documented population in Dinosaur National Monument also is considered gone.

The U.S. Fish and Wildlife Service also is considering reclassifying another endangered fish that calls the Colorado River home to threatened. Chart was unsure when that proposal on the razorback sucker will be available for public comment. 

The two other endangered fish species in the Colorado River basin, the bonytail and the Colorado pikeminnow, are unlikely to be considered for downlisting in the near future, Chart said. The bonytail was up for review in 2019, and due to struggling populations the agency declined to pursue moving the fish from endangered to threatened. The pikeminnow could be up for a similar review as early as this year, Chart said.

The Associated Press contributed reporting to this story. Some content copyright The Associated Press, 2020.