Thu. Sep 21st, 2023

PAGE, Ariz. (AP) — The Nationwide 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 therapy, the company stated Friday.

A substance deadly to fish however accepted by federal environmental regulators referred to as rotenone might 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 therapy 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 12 months.

The trouble will “be fastidiously deliberate and carried out to attenuate publicity” to people in addition to “fascinating fish species,” in line with the Nationwide Park Service. An “impermeable material barrier” might be erected on the mouth of the slough to forestall crossover of water with the river.

As soon as the therapy is full, one other chemical might be launched to dilute the rotenone, the park service stated.

Prior to now, smallmouth bass have been sequestered in Lake Powell behind Glen Canyon Dam, which had served as a barrier to them for years. However final summer season, they have been discovered within the river under the dam.

Resulting from local weather change and drought, Lake Powell, a key Colorado River reservoir, dropped to traditionally low ranges final 12 months, making it not as a lot of an impediment to the smallmouth bass. The predatory fish have been in a position to 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 Heart for Organic Range pointed to knowledge from the Nationwide Park Service launched Wednesday exhibiting the smallmouth bass inhabitants greater than doubled up to now 12 months. The group additionally stated there nonetheless have been no timelines given on modifying the realm under the dam.

“I’m afraid this bass inhabitants increase portends a wholly avoidable extinction occasion within the Grand Canyon,” stated Taylor McKinnon, the Heart’s Southwest director. “Shedding the humpback chub’s core inhabitants places all the species in danger.”

Conservation teams additionally proceed to criticize the 2021 resolution to downgrade the humpback chub from endangered to threatened. On the time, federal authorities stated the fish, which will get its identify from a fleshy bump behind its head, had been introduced again from the brink of extinction after many years of protections.

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