PAGE, Ariz. — The National Park Service will renew efforts to rid an space of the Colorado River in northern Arizona of invasive fish by killing them with a chemical remedy, the company mentioned Friday.
A substance deadly to fish however authorized by federal environmental regulators referred to as rotenone can be disseminated beginning Aug. 26. It’s the newest tactic in an ongoing battle to maintain non-native smallmouth bass and inexperienced sunfish at bay under the Glen Canyon Dam and to guard a threatened native fish, the humpback chub.
The remedy would require a weekend closure of the Colorado River slough, a cobble bar space surrounding the backwater the place the smallmouth bass have been discovered and a brief stretch up and downstream. Chemical substances have been additionally utilized final yr.
The effort will “be carefully planned and conducted to minimize exposure” to people in addition to “desirable fish species,” in keeping with the National Park Service. An “impermeable fabric barrier” can be erected on the mouth of the slough to forestall crossover of water with the river.
Once the remedy is full, one other chemical can be launched to dilute the rotenone, the park service mentioned.
In the previous, smallmouth bass have been sequestered in Lake Powell behind Glen Canyon Dam, which had served as a barrier to them for years. But final summer time, they have been discovered within the river under the dam.
Due to local weather change and drought, Lake Powell, a key Colorado River reservoir, dropped to traditionally low ranges final yr, making it not as a lot of an impediment to the smallmouth bass. The predatory fish have been capable of method the Grand Canyon, the place the biggest teams of the traditional and uncommon humpback chub stay.
Environmentalists have accused the federal authorities of failing to behave swiftly. The Center for Biological Diversity pointed to information from the National Park Service launched Wednesday exhibiting the smallmouth bass inhabitants greater than doubled previously yr. The group additionally mentioned there nonetheless have been no timelines given on modifying the realm under 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 population puts the entire species at risk.”
Conservation teams additionally proceed to criticize the 2021 resolution to downgrade the humpback chub from endangered to threatened. At the time, federal authorities mentioned the fish, which will get its title from a fleshy bump behind its head, had been introduced again from the brink of extinction after a long time of protections.
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