Chemical treatment to be deployed against invasive fish in Colorado River

PAGE, Ariz. — The National Park Service will renew efforts to rid a space of the Colorado River in northern Arizona of invasive fish via killing them with a chemical treatment, the company mentioned Friday.

A substance deadly to fish however licensed via federal environmental regulators referred to as rotenone will be disseminated beginning Aug. 26. It’s the most recent tactic in an ongoing fight to stay non-native smallmouth bass and inexperienced sunfish at bay underneath the Glen Canyon Dam and to give protection to a threatened local fish, the humpback chub.

The treatment would require a weekend closure of the Colorado River slough, a cobble bar space surrounding the backwater the place the smallmouth bass had been discovered and a brief stretch up and downstream. Chemical elements had been additionally applied remaining yr.

The effort will “be carefully planned and conducted to minimize exposure” to humans as well as “desirable fish species,” in accordance to the National Park Service. An “impermeable fabric barrier” will be erected at the mouth of the slough to prevent crossover of water with the river.

Once the treatment is complete, another chemical will be released to dilute the rotenone, the park service said.

In the past, smallmouth bass were sequestered in Lake Powell behind Glen Canyon Dam, which had served as a barrier to them for years. But last summer, they were found in the river below the dam.

Due to climate change and drought, Lake Powell, a key Colorado River reservoir, dropped to historically low levels last year, making it no longer as much of an obstacle to the smallmouth bass. The predatory fish were able to approach the Grand Canyon, where the largest groups of the ancient and rare humpback chub remain.

Environmentalists have accused the federal government of failing to act swiftly. The Center for Biological Diversity pointed to data from the National Park Service released Wednesday showing the smallmouth bass population more than doubled in the past year. The group also said there still have been no timelines given on modifying the area below the dam.

“I’m afraid this bass population boom portends an entirely avoidable extinction event in the Grand Canyon,” mentioned Taylor McKinnon, the Center’s Southwest director. “Losing the humpback chub’s core inhabitants places all of the species in peril.”

Conservation teams additionally proceed to criticize the 2021 determination to downgrade the humpback chub from endangered to threatened. At the time, federal government mentioned the fish, which will get its identify from a fleshy bump in the back of its head, have been introduced again from the threshold of extinction after many years of protections.