Here’s What It Takes To Keep #ColoradoRiver Fish From Going Extinct — KUNC #COriver

From KUNC (Luke Runyon):

The Colorado River is one of the most engineered river systems in the world. Over millions of years, the living creatures that call the river home have adapted to its natural variability, of seasonal highs and lows. But for the last century, they have struggled to keep up with rapid change in the river’s flows and ecology.

Dams throughout the watershed create barriers and alter flows that make life hard for native fish. Toss in 70 non-native fish species, rapidly growing invasive riparian plants and a slurry of pollutants, and the problem of endangered fish recovery becomes even more complex. The river system is home to four fish species currently listed as endangered: the razorback sucker, Colorado pikeminnow, bonytail and humpback chub.

For decades, millions of dollars have been spent on boosting populations of the river’s fish species on the brink of extinction. While scientists are learning what helps some species survive in the wild, others are still struggling.

Ouray National Fish Hatchery. Photo credit: USFWS

“Darling little divas”

Much of the work of keeping these fish from going extinct is centered in a handful of hatcheries scattered throughout the West. One such hatchery, the Ouray National Fish Hatchery, is situated along the Green River in eastern Utah. It’s a squat, unassuming building next to a series of ponds where two of the river’s endangered fish — the bonytail and razorback sucker — are raised.

Inside, the room is filled with aqua-colored tubs of water. A pipe feeds each tub with fresh water and creates a whirlpool, simulating a river’s flow. Above the tubs, lights automatically dim up and down to give the fish some semblance of a sunrise, high noon and sunset.

U.S. Fish and Wildlife Service biologist Matt Fry peers into one of the tubs and warns not to do it too quickly to keep from stressing them out. “When they see you, they’ll scatter,” he said.

Fry is the acting manager of this hatchery. This kiddie pool-sized tub is full of bonytail, so named for their slender, tapered bodies.

“I call these guys my darling little divas because you really got to treat them with kid gloves,” Fry said.

A couple decades ago, bonytail were nearly extinct, the last few scooped up from Lake Mohave in the Colorado River’s lower reaches. Hatcheries like this one have kept them alive, while scientists tried to figure out the best way to help them survive and overcome the challenges humans keep throwing at them out in the wild…

“Hurdles to overcome”

That is the question for Tildon Jones, Fry’s colleague at the Fish and Wildlife Service. He’s a habitat coordinator for the agency, and looks for ways to help the endangered fish complete their life cycle in the wild, not just rely on people to keep raising them in hatcheries.

On a bluff overlooking the Green River near the hatchery, Jones points out the features of a riverside wetland. The river — a majority tributary to the Colorado — makes a narrow U-shaped bend, and in the middle is a wetland.

“The river would come up and flood these areas regularly in the past,” Jones said, pointing to the lines of cottonwood trees over a chorus of sandhill cranes that has taken up residence nearby.

Green River Basin

This stretch of the Green, with its abundance of low-lying wetlands, used to be a haven for the razorback sucker, known for its bony hump and down-turned vacuum-like mouth. The fish adapted to the Colorado River’s wild swings between high and low flows by spawning just before its annual spring snowmelt rise. Those flood waters would carry the tiny, just-born fish into protected riverside ponds to grow. At that point, the larval fish look like a grain of rice with two black dots for eyes…

But the Green River hasn’t acted like its former self in more than 50 years. The Flaming Gorge Dam just upstream holds back those flood waters, and regulates the river’s flow, making the tiny razorbacks less likely to end up in wetlands, and more vulnerable to non-native fish that gobble them up…

The fish don’t just have one thing working against them, but a confluence of factors keeping them from thriving. If it were just the restricted, regulated flows or just the addition of non-native fish predators, the problem might be easier to solve, Jones said.

Since 2012, the Fish and Wildlife Service along with other partners in the Upper Colorado River Endangered Fish Recovery Program have turned their focus to managing wetlands to give razorbacks a better chance of reproducing in the wild, and giving juvenile fish the opportunity to grow.

Canals move river water into the wetland during high flows, or coordinated releases from Flaming Gorge reservoir, and metal screens keep out the predatory fish. Researchers can then keep an eye on the growing razorbacks before releasing them back into the river.

After seeing some initial success in this approach, and seeing adult razorback populations stabilize due to stocking, Jones’s agency is proposing to move razorbacks from an endangered status to threatened…

Katie Creighton and Zach Ahrens both native aquatics biologists for Utah Division of Wildlife Resources (UDWR) standing on the temporary Matheson screen. The Nature Conservancy and UDWR partnered together to build the structure to allow the endangered razorback sucker larvae to enter the Scott M. Matheson Wetlands Preserve without the predators also coming in. Courtesy & Copyright Katie Creighton, Photographer via Utah Public Radio

Reconnecting the river to its wetlands

After seeing managed wetlands demonstrate successes on the Green River, The Nature Conservancy’s Linda Whitham says it made sense to replicate the idea on a stretch of the Colorado River near Moab, Utah. The environmental group receives funding from the Walton Family Foundation, which also supports KUNC’s Colorado River reporting.

On a warm fall day, big yellow dump trucks moved dirt, excavated as part of a pond expansion at the Matheson Wetlands Preserve. A deepened channel and water control structure with a screen to keep out the predatory fish were also added.

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