Humpback chub now a threatened, not endangered, fish — The #GrandJunction Daily Sentinel

Humpback chub (Gila cypha) as seen in the Little Colorado River, Summer 2021.© Freshwaters Illustrated / USFWS

From The Grand Junction Daily Sentinel (Dennis Webb):

A rapids-loving, odd-looking native fish found locally in the Colorado River is now officially considered to be at a reduced risk of extinction.

The U.S. Fish and Wildlife Service on Friday said it has reclassified the humpback chub from endangered to threatened under the Endangered Species Act, thanks to significant progress made by conservation and recovery efforts of federal agencies, states, tribal entities and private partners.

“It’s a major milestone that we feel very proud of,” Kevin McAbee, acting director of the Upper Colorado River Endangered Fish Recovery Program, told The Daily Sentinel. “We believe that it demonstrates the collaborative conservation efforts that we’ve been undertaking with our partners over the last three-decades-plus are working. It’s really something that we’ve been working towards for many years and we’re just very excited about it.”

[…]

Feeding on insects, crustaceans and plants, the humpback chub can live 20 to 40 years, grow up to 19 inches long and produce up to 2,500 eggs per year. A warm-water species, it is uniquely adapted to live in the turbulent whitewater found in rivers’ rocky canyon areas, according to the Fish and Wildlife Service. Its namesake, fleshy lump behind its head evolved to make it harder to be eaten by predators, and large, curved fins let it stay in place in swift currents.

These traits have helped it survive in the Black Rocks area of the river in western Mesa County and in Westwater Canyon just across the Utah border, where the Fish and Wildlife Service says the most recent estimates indicate there are populations of 430 and 3,300 adults, respectively. The Westwater Canyon population has been growing and the Black Rocks numbers are stable, but a large number of juveniles may boost the Black Rocks population in the future.

Other stable populations exist at the Desolation/Gray canyons area on the Green River in Utah and Cataract Canyon on the Colorado River in Utah. The Grand Canyon is home to the largest number of fish, including an estimated 12,000 in a core area in the Little Colorado River and the Colorado River around their confluence…

Globally, the fish exists only in that handful of core population areas. Another population in Dinosaur National Monument appears to have died out. McAbee said the Westwater and Black Rocks populations combined are the largest population upstream of Lake Powell, making them the home of the largest combined population in the world of humpback chub outside of the Grand Canyon, and an important core population just downstream of Grand Junction…

Two multi-stakeholder efforts, the Upper Colorado River program and Glen Canyon Dam Adaptive Management Program, have worked to try to help recover the species. In the Upper Colorado River, these efforts have included protecting river flows; managing and removing predatory, nonnative fish; and installing and operating fish passage structures where dams otherwise can impede fish travel.

Water-release measures involving upstream reservoirs have helped manage river flows to benefit the fish despite drought conditions that largely have prevailed over the last two decades. The Fish and Wildlife Service concluded that current river flows and temperatures are largely adequate despite climate change, so it doesn’t put the fish at immediate risk of extinction, which would mean it’s endangered. But the agency found that uncertainty about the possible severity of future water-supply declines poses a threat to the fish in the future, so it is likely to become endangered in the foreseeable future — the criteria for determining that it is threatened…

Another uncertainty surrounds the future of conservation efforts in the Upper Colorado River Basin because the recovery program there currently is scheduled to expire in 2023…

“However, commitment to continue the decades-long partnership is strong, as demonstrated by ongoing efforts to extend the partnership beyond 2023,” the Fish and Wildlife Service says in its final rule on the fish’s downlisting…

A further challenge for the program that the Fish and Wildlife Service is monitoring is the status of its funding.

Federal hydropower revenue that has helped support the program is threatened because falling reservoir levels are jeopardizing hydropower generation.

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