Razorback sucker: Wetlands fish nursery shows promise as habitats keep changing

Zach Ahrens is one of the Utah Division of Wildlife Resources scientists working to help the endangered razorback sucker sustain itself. Photos courtesy of DWR

The endangered razorback sucker has lived in the Colorado River and its tributaries for millions of years, but its existence has been threatened for decades due to rapidly changing habitat and the introduction of predatory nonnative fish.

For Zach Ahrens, a native aquatics biologist with the Utah Division of Wildlife Resources’ Moab Field Office, saving the funny looking fish is more than a job – it’s his mission.

“For me, what I think is really cool about the razorback sucker is it is unique to the Colorado River Basin, it’s long-lived, it lives for decades; and razorback suckers have shown up in the fossil record for millions of years. Plus, it’s swimming right in our backyard,” he said during a recent interview.

Razorback sucker

DWR and The Nature Conservancy, which has oversight of a portion of the Matheson Preserve wetlands area while DWR manages another, joined together to build a fish nursery.

The work on that project has been going on for a number of years, but already the concrete structure is providing a safe haven for razorback sucker larvae to grow unmolested – but they just haven’t lived beyond the larval stage.

Ahrens said the razorback is no longer “on the brink of imminent extinction,” thanks to two places where they are raised – in Vernal and Grand Junction, Colorado – but efforts by some to have the fish delisted as an endangered species are premature, he said.

“We see all sorts of reproduction with the larvae, but they don’t make it past that stage,” he said. “There is no survival beyond that.” It’s not self-sustaining, but there are plenty of stocked razorbacks, said Ahrens, a fish that can live up to 40 years.

Ahrens said a recent sample of larvae proved to be razorback sucker at the nursery, giving “some indication it’s working as we hoped it would,” he said. “For it to work the way we want we need gates and fish screens to keep out large-bodied fish, particularly nonnative fish so the larvae can survive and grow fast … we have to keep nonnative predators out.” This nonnative fish include bass, sunfish, catfish and bullhead.

Currently, there are only two Colorado River-fed lakes that feature wild razorback sucker – Mead and Mojave, both on the Nevada-Arizona border in the lower basin. It’s been listed as a protected fish in Utah for nearly 50 years and has been on the federal Endangered Species List since 1991.

“There’s probably more nonnative fish than native fish in the Colorado these days” said Ahrens. “The other native fish, all endangered, include the humpback chub, the Colorado pike minnow and the bonytail.

Ironically, the razorback sucker and its ridged back and floppy lips was born to thrive in the waters of the American Southwest, but the growth of industry and agriculture have altered the flow of the river, making it difficult for the fish to find the calm, slow-moving water it needs for larvae habitat. Tamarisk trees, another nonnative species, grow in great numbers along the riverbanks, also robbing the razorback of habitat.

While tamarisk are being removed, they’ve proliferated over the years. Other work intended to aid recovery includes managing water to provide beneficial water flow, construct fish passages and screens at major diversion dams to provide endangered fish with access to critical habitat, restore the floodplain, monitor fish population and manage predatory nonnative fish.

The stocked fish tend to thrive, with evidence showing they move from the Colorado to the Green and Gunnison rivers and they are clearly reproducing. The goal is to provide the larvae the same fighting chance.

All of this, of course, makes the Matheson Preserve sort of the Alamo for the razorback, a place to make one last desperate stand.