Biologists’ fears identified in the lower Colorado River


Denver (AP) — For Jeff Arnold, a fishery biologist at the National Park Service, that was a moment he was afraid of. He was pulling a net in the shallow backwaters of the lower Colorado River last week and found three young fish that did not belong to it. “Call me when you receive this!” He sent a message to his colleague and took a picture.

A few minutes later, the park’s service confirmed their worst horror. Smallmouth bass may have been actually discovered and bred in the Colorado River beneath Glen Canyon Dam.

They may be beloved sportsfish, but smallmouth bass are a lifelong recovery for humpback chubs, ancient endangered fish native to rivers, and biologists like Arnold. Feast on working hard. Predators caused havoc in upstream rivers, but were detained in the bays of Lake Powell, where Glen Canyon Dam has served as a barrier for years — until now. The recent sharp decline in reservoirs allows these introduced fish to pass through the dam and approach where the largest group of squalius remains, further downstream of the Grand Canyon.

So Brian Healy has worked with Hump Back Chub for over a decade to establish the Native Fish Ecology and Conservation Program.

“It’s pretty good to see all the efforts and efforts spent to remove other invasive species and move the population to protect the fish, and see that all the efforts are really overturned very quickly. It’s devastating, “Healy said.

As the reservoir drops, non-native fish that live in the warm surface waters of Lake Powell approach the dam and its penstock. An underwater steel pipe that carries water to a turbine, which produces hydroelectric power and is discharged on the other side.

Bass and other predatory fish sucked into the penstock, survived under the dam, and continued to breed, creating open lanes to attack chubs and other natives, unleashing years of restoration work. , The aquatic ecosystem of the Grand Canyon can be destroyed. The spread of the river is still dominated by native species.

Endangered chubs decades ago have returned in moderation thanks to fish biologists and other scientists and engineers. Agencies spend millions of dollars each year to control intruders upstream of the river.

Under the Endangered Species Act, government agencies are required to operate in a manner that does not “endanger” the listed animals. This includes infrastructure.

The agency was prepared for this moment, even before the smallmouth bass were found spawning under the dam. The Utah State University has recently asked a team of researchers at Utah State University to: Map exotic fish on Lake Powell Determine which one can pass the dam first.

Earlier this year, the Task Force gathered quickly to address the urgency of low waters for native fish. Federal, state, and tribal leaders August draft plans including solutions for policy makers who intend to delay, delay, and respond to the threat of smallmouth bass and other predators under the dam. Will be announced at.

There are a variety of solutions, but often require significant infrastructure changes.

Meanwhile, the National Park Service, the US Geological Survey, and the Arizona Game and Fish Division are working swiftly to contain this issue. At the emergency meeting, we decided to strengthen surveillance in other shallow areas and block the entire backwater where smallmouth bass were found so that they could not swim into the river.

“Unfortunately, the only blocknet we have is a fairly large mesh, so we can’t stop these little fish from passing through, but we can prevent adults from coming back,” Arnold said. .. Financial resources.

Experts say leaving more water in Lake Powell is the best solution to ensure that cold water is released from the dam, but doing so in rivers under so much stress. Is difficult.

Last month, the Home Office announced that seven western states that depend on the water of the Colorado River need to devise ways to save up to 4 million acre-foot of water in 2023. Federal intervention. It’s unclear where that saved supply will be stored, but Healy says he wants Lake Powell to be considered.

“If you want to protect some of the value that the Grand Canyon National Park was founded in, you really need to think about how water is stored,” Healy said. “The problem must be in the table.”


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