Closed Circuit

​By Philip Reed

In April, the U.S. Fish and Wildlife Service announced that the humpback chub, a federally protected fish living in the Colorado River, would be downlisted from endangered to threatened status as a result of its increasingly healthy population. In October, the razorback sucker received similarly good news, making it the second of the four native endangered Colorado River fish to be proposed for this status change in 2018.

Downlistings of this kind come about as the result of successful conservation efforts between the FWS and other organizations, including WAPA, where biologists and others work tirelessly to restore and support endangered and threatened fish populations. 

“Our partners along the Colorado River have restored flow, created habitat, removed non-native predators, and reestablished populations across these species’ range,” said Upper Colorado River Endangered Fish Recovery Program Director Tom Chart. “These partnerships have improved conditions, proving long-term commitments are a key component to recovery.” 

The razorback sucker, which gets its name from the bony keel behind its head, has historically occupied an area stretching from Wyoming to Mexico. 

The FWS’ recently completed species status assessment and five-year status review concluded that the current risk of extinction for the razorback sucker is low and the species is no longer in danger of extinction. The assessment also explained that large populations of adult razorback suckers have been reestablished in the Colorado, Green and San Juan Rivers. Populations are also present in lakes Powell, Mead, Mohave and Havasu.

“In the Green River in the mid-1990s, the number of adults captured in a year could be counted on one hand,” the FWS said in their news release. “Today the population has rebounded to over 30,000 adults.” 

The Denver Post reports that some estimates in the 1980s placed the population of the razorback sucker at around 100. 

Their numbers have bounced back to between 54,000 and 59,000 today, thanks to a multimillion-dollar effort that brought together hatcheries, dam operators, landowners, Native American tribes and state and federal agencies. 

One wetland along the Green River produced 2,000 young razorback suckers in the past five years, which the FWS described as being “the first substantial number of juveniles seen in over 30 years in the upper basin.” 

The FWS attributes much of this growth to the success of hatchery and stocking programs, but continuing management efforts are needed to help the species survive predation and other factors in sufficient numbers to reach adulthood. 

“It’s a work in progress,” said Chart. “We get more fish out in the system, they’re showing up in more places, they’re spawning in more locations.”

Hatcheries are not singular solutions, however. The first-year survival rate of hatchery fish in the wild is only about 20 percent. For those fish that survive the first year, however, their survival rate rockets to 80 percent. 

The razorback sucker is especially vulnerable to non-native predators, which were originally introduced as game fish without the knowledge that they would decimate the native fish. Changes in river flows over time also contributed to the decline of the fish’s population. 

“Changing the fish from endangered to threatened will allow more flexibility in the way it is protected,” said Upper Colorado River Endangered Fish Recovery Program Deputy Director Kevin McAbee. He explained that under endangered status, individual fish must be protected. Threatened status, however, allows biologists to focus on taking steps to improve the overall population. 

The FWS’ efforts to propose reclassification and revise the recovery plan will continue into 2019. The reclassification rule and the revised recovery plan will be made available for public comment.

Note: Reed is a technical writer who works under the Wyandotte Services contract. Data and definitions in this article are adapted from information provided by the U.S. Fish and Wildlife Service.

Last modified on March 8th, 2024