Oddlooking sucker fish pulled back from brink of extinction
Another rare Colorado River fish has been pulled back from the brink of extinction, the second comeback this year for a species unique to the American Southwest.
The U.S. Fish and Wildlife Service announced Thursday it will recommend reclassifying the ancient and oddlooking razorback sucker from endangered to threatened, meaning it is still at risk of extinction, but the danger is no longer immediate.
Hundreds of thousands of razorbacks once thrived in the Colorado River and its tributaries, which flow across seven states and Mexico.
By the 1980s, they had dwindled to about 100. Researchers blame nonnative predator fish that attacked and ate the razorbacks and dams that disrupted their habitat.
Their numbers have bounced back to between 54,000 and 59,000 today, thanks to a multimilliondollar effort that enlisted the help of hatcheries, dam operators, landowners, American Indian tribes and state and federal agencies.
“It’s a work in progress,” said Tom Chart, director of the Upper Colorado River Endangered Fish Recovery Program. “We get more fish out in the system, they’re showing up in more places, they’re spawning in more locations.”
Chart’s program oversees the campaign to restore the razorback sucker and three other fish, all of them found only in the Colorado River system.
In March, the Fish and Wildlife Service recommended changing the humpback chub from endangered to threatened. It takes 18 to 24 months to complete the process, including a public comment period.
The razorback sucker’s name comes from a sharpedge, keellike ridge along its back behind its head. Chart thinks the ridge may have evolved to help the fish stay stable in the turbulent waters of the Colorado River. The fish can grow up to 3 feet long and live up to 40 years.
Razorbacks have been around for between 3 million and 5 million years, but trouble arrived as the population expanded in the Southwest. State and federal agencies began introducing game fish into the Colorado River without realizing they would devour the native fish, Chart said. A spurt of dambuilding was a boon to cities and farms but interrupted the natural springtime surge of melting snow, which in turn shrank the floodplains that provided a safe nursery for young razorbacks.
Dams also made parts of the rivers too cold for razorbacks, because they release water from the chilly depths of reservoirs. And they blocked the natural migration of the fish.
By the late 1980s, most of the wild razorbacks were old, an ominous sign they were no longer reproducing, Chart said. The Fish and Wildlife Service began capturing the remaining wild razorbacks and moving them to hatcheries to begin rebuilding the population.
The agency designated razorbacks an endangered species in 1991, although Utah and Colorado enact ed state protections earlier.
Biologists began restocking rivers with hatcheryraised razorbacks in 1995. Now, about 55,000 are released into the Colorado River and its tributaries annually.
The Fish and Wildlife Service began working with dam operators to time water releases to help razorbacks spawn and restore floodplains for them to mature. Some dams were modified to help razorbacks to get by.
Wildlife officials began reining in nonnative predator fish with nets and screens to keep them from escaping reservoirs, or removing them by electrofishing — stunning them with electricity and euthanizing them with an overdose of anesthetic.
Changing the fish from endangered to threatened will allow more flexibility in the way it is protected, said Kevin McAbee, deputy director of the recovery program.
Under endangered status, individual fish have to be protected, but threatened status means biologists can take steps to improve the overall population even if some fish might be hurt, McAbee said.
Razorbacks still face challenges. The firstyear survival rate of hatchery fish, each roughly 14 inches long, is about 20 percent or less in the wild, Chart said. It climbs to 80 percent after that. Drought, climate change and increasing human demand are straining the rivers, which makes it harder for fish to survive.