Officials release initial results of Lake Powell survey – St George News

ST. GEORGETeams of volunteer biologists and anglers recently concluded Lake Powell’s annual fish survey, and their early results reflect a year of extremely poor water.

Aquatic biologist Nic Braithwaite sorts nets on a boat driven by Richard Hepworth, aquatics manager for the Utah Division of Wildlife Resources Southern Region office, Lake Powell, Utah, October 25, 2021 | Photo courtesy of Phil Tuttle, St. George News

Richard Hepworth, aquatics manager at the Southern Region office of the Utah Division of Wildlife Resources, said the two-week survey is conducted each year in late October and early November, allowing fish populations time laid to stabilize after spawning.

“The one thing that stuck out to me the most was the lack of young fish of the year,” Hepworth said. “Young fish just haven’t survived this year, and that happens sometimes – especially when water levels drop like they have this year. It’s not necessarily a bad thing if it happens a year, but if it happens again in the next two years, it will be concerning.

Working in teams of five to 10 people at several locations around the lake, biologists used 100-foot gillnets set along the waterline overnight to capture a sample of the fish population. Every morning, workers scooped up the trapped fish, weighed them, checked their stomach contents, and then filleted the fish to yield the meat.

A full analysis of the survey will be released in the spring of 2021. While early results spelled trouble for young fish in the lake, the results were quite different for mature specimens caught.

“The adult fish in the lake are doing pretty well because they have plenty of food available to them,” Hepworth said, but added that if there is another drought year, “even the adult fish will start to struggle.” .

“If there’s one thing at Lake Powell that has remained constant for 40 to 50 years, it’s that water levels dictate how the fishery evolves.”

Biologist Adam Kavalunas worked alongside volunteers and others with the Utah Division of Wildlife Resources to investigate fish in Lake Powell, Utah, October 25, 2021 | Photo courtesy of Phil Tuttle, St. George News

In addition to providing nutrients and prey for fish, the Colorado and San Juan rivers feed the lake itself. For this reason, this winter’s snowpack in the mountains of Colorado and Wyoming will have a big impact on next year’s fish survey.

Another continuing trend observed by biologists and volunteers is the dominance of non-native species. Before the dam was installed, native fish like shavedback sucker and roundtail chub swam in the silty flows of the Colorado and San Juan rivers that now feed the lake.

Walleye, European carp, and catfish escaped into the Colorado River prior to dam completion and battled native species until dam completion. Now these new fish are flourishing alongside purposely introduced game species like striped bass, threadfin shad and largemouth bass.

“There are very few native species left in Lake Powell,” Hepworth said. “We sometimes catch some of the native species near the mouth of the San Juan or the mouth of the Colorado. Those are the most productive parts of the lake and we have a lot more fish in those areas.”

Located in the Glen Canyon National Recreation Area, Lake Powell is the second largest man-made reservoir in the United States. The lake is the centerpiece of a recreation area that sees more than two and a half million visitors each year, according to National Park Service data.

A striped bass (striper) caught using gillnets placed as part of the annual survey of fish populations in Lake Powell, Utah, October 27, 2021 | Photo courtesy of Phil Tuttle, St. George News

Glen Canyon and Lake Powell generated approximately $300 million in economic impact in 2020, earning them the top spot among Utah’s national parks. More than 14% of this impact came from the recreational industries, which include the large number of anglers who visit each year.

The Utah Wildlife Division tracks fishing in the recreation area, and Hepworth said the last large-scale survey of anglers was conducted in 2018. At that time, Lake Powell had 1 to 1.2 million fishing hours per year, which equates to approximately 1.5 million. fish caught annually.

“These are huge numbers that are really hard to think about,” Hepworth said. “Lake Powell is, in my opinion, one of the most underrated and incredible fisheries we have in the western United States. And it’s all done with very little management and very little fresh for our anglers because we don’t have to stock the lake – it’s all natural Producing so many fish that can be harvested, brought home and eaten is pretty amazing.

Copyright St.George News, LLC, 2021, all rights reserved.

Previous Biden's choice to lead US Fish and Wildlife promises 'collaborative conservation' at agency
Next You can help protect a species of fish vital to ocean ecosystems