Humpback chub

HUMPBACK CHUB

The U.S. Fish and Wildlife Service on Tuesday formally proposed downlisting the status of the humpback chub from endangered to threatened, following through on plans announced two years ago for a fish found in the Colorado River, including in Mesa County.

In doing so, the agency cited the stability of the species’ largest population in the Grand Canyon, home to about 12,000 adult humpback chubs, and the persistence of four smaller populations. These are found in the Black Rocks stretch of the river in far-western Mesa County, the Westwater Canyon stretch just downstream in Utah, Cataract Canyon in Utah and in the Desolation and Gray canyon stretches of the Green River in Utah.

The humpback chub, a member of the minnow family, was first documented in the Grand Canyon in the 1940s and in the Upper Colorado River Basin in the 1970s, according to a Fish and Wildlife Service news release. It was federally listed as endangered in 1967, even before the passage of the Endangered Species Act.

It is uniquely adapted to swift, turbulent, whitewater stretches of canyon-bound river, the agency says. It gets its name from the fleshy hump behind its head, which along with its large, curved fins help it maintain its position in fast currents. It can grow up to 19 inches long and live 20 to 40 years, but has suffered from dam-building and other impacts such as the introduction of non-native predators it never evolved to have natural defenses against.

The fish is one of four endangered native species that the Upper Colorado River Endangered Recovery Program, a partnership of federal and state agencies and other entities, is trying to recover. The other fish include the bonytail, Colorado pikeminnow and razorback sucker.

In 2018, the Fish and Wildlife Service completed species status assessments for the humpback chub and razorback sucker and said it was proposing them for downlisting from endangered to threatened. With this week’s action, the agency is formally moving ahead with that proposal in the case of the humpback chub, with its announcement opening a 60-day comment period.

Agency spokesman Michael D’Agostino said a proposal hasn’t been released for comment yet in the case of the razorback sucker.

Efforts to help the humpback chub recover have included boosting river flows through releases from reservoirs, including from those in the Aspinall Unit on the Gunnison River, and on removing predators and introducing humpback chub to new locations in its native range.

According to a Federal Register document scheduled for publication today, the Black Rocks population is estimated to have around 425-450 adults, and the Westwater population, around 2,800 adults. Both of those populations are considered to be stable. A small refuge population from the Black Rocks population is living in the Horsethief ponds near Grand Junction. Refuge populations can help protect the genetic diversity of the species and provide a source for stocking fish into its habitat.

The Fish and Wildlife Service based its proposal to list the fish as threatened rather than endangered on its conclusion that the fish isn’t currently in danger of extinction, but still likely to become in danger of extinction within the foreseeable future throughout its range.

The Center for Biological Diversity said in a news release that the Trump administration is making its proposal even though a population in Dinosaur Monument has died out since 2002 and other upper-basin populations have stabilized at populations below the minimum viability requirements set out by the fish’s current recovery plan.

“The humpback chub remains very much endangered,” Taylor McKinnon of the Center for Biological Diversity said in the release. “One of the six remaining populations was recently lost, and the remaining fish face multiple threats, from climate change to new dams. This is a disturbing attack on an endangered species by the Trump administration, which has been systematically removing protections from our waters and wildlife.”

McKinnon’s group is particularly worried about two proposed dams on the Little Colorado River that it says would harm or destroy the fish’s critical habitat there.

D’Agostino said his agency will welcome additional scientific information and other public comments over the next 60 days, and those comments will factor into its eventual decision.

Part of the agency’s proposal is to no longer regulate “take,” meaning harm or mortality of the fish, associated with certain conservation actions that benefit it, and to reduce regulatory requirements for state agencies and other nonfederal stakeholders to create refuge populations, expand the fish’s range and remove non-native species.

Incidental take of the humpback chub during catch-and-release fishing targeting other fish where its core populations live wouldn’t be prohibited.

For more information on the Fish and Wildlife Service proposal, and how to comment, visit https://coloradoriverrecovery.org/general-information/the-fish/humpback-chub.html.

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