ST. GEORGE — Teams of biologists and volunteer anglers recently concluded the annual survey of fish in Lake Powell, and their early findings reflect an extremely poor water year.
Richard Hepworth, aquatics manager with the Utah Division of Wildlife Resources Southern Region office, said the two-week survey is conducted each year at the end of October and the beginning of November – allowing time for spawned fish populations to stabilize after spawning.
“The one thing that stood out to me the most was the lack of young-of-the-year fish,” Hepworth said. “The young fish just did not survive this year, and that happens occasionally – especially when you have water levels dropping like they did this year. It’s not necessarily a bad thing if it happens one year, but if it happens again for the next couple years it’ll be concerning.”
Working in crews of five to 10 people at multiple locations around the lake, biologists used 100-foot gillnets strung out along the waterline overnight to capture a sample of the fish population. Each morning the workers would collect the snared fish, weigh them, check their stomach content and then fillet the fish to donate the meat.
A full analysis of the survey will be published in spring of 2021. While the early findings spell trouble for the lake’s young fish, the results were quite different for the mature specimens caught.
“The adult fish in the lake are doing quite well because they’ve had a lot 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’s been consistent over 40-50 years is water levels dictate how the fishery is doing.”
In addition to supplying nutrients and prey for the fish, the Colorado and San Juan rivers sustain the lake itself. For that reason, this winter’s snowpack in the mountains of Colorado and Wyoming will have a great impact on next year’s fish survey.
Another continuing trend observed by the biologists and volunteers is the dominance of nonnative species. Before the dam was installed, native fish like the razorback sucker and roundtail chub swam through 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 before the dam was completed and struggled with native species up until the dam’s completion. Now these newcomer fish flourish alongside purposefully introduced game species like striped bass, threadfin shad and largemouth bass.
“There are very few native species left in Lake Powell,” Hepworth said. “We do occasionally 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 artificial reservoir in the United States. The lake serves as the central feature of a recreation area that welcomes more than two and half million visitors each year, according to data from the National Park Service.
Glen Canyon and Lake Powell generated around $300 million in economic impact in 2020, earning it the top spot among Utah’s national parks. Over 14% of that impact came from recreation industries, which includes the large number of anglers that visit each year.
The Utah Division of Wildlife tracks fishing in the recreation area, and Hepworth said the last large-scale angler survey was conducted in 2018. At that time, Lake Powell saw 1 million to 1.2 million angler hours per year, which equates to about 1.5 million fish harvested annually.
“They’re huge numbers that are really hard to even think about,” Hepworth said. “Lake Powell is, in my opinion, one of the most underrated and unbelievable fisheries we have in the Western United States. And that’s all done with very little management and very little cost to our anglers because we don’t have to stock the lake – it’s all natural. To produce that many fish that can be harvested, taken home and eaten is pretty amazing.”
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