When Utah Division of Wildlife Resources (UDWR) discovered someone had illegally put walleye in Red Fleet Reservoir in 2002, Recovery Program stakeholders knew they had problem. Walleye are top predators that consume other fish and can lay thousands of eggs. Walleye reproduced in Red Fleet and increased in numbers. Then they began consuming trout, decreasing the family fishing opportunities at the state park. In 2014, Recovery Program research concluded walleye were escaping the reservoir, where they were eating native species in the Green River. A solution was needed.
UDWR aquatics staff in the Northeastern Region, responsible for management of Red Fleet Reservoir, had a big task ahead of them – replacing the illegal walleye with fish that were exciting to anglers AND compatible with downstream endangered species recovery. Before they did any work on the water, they met with anglers to find out what fish the local community would like to catch. Out of that conversation they learned that anglers wanted to catch walleye and other large predator species. How were they to provide large predatory fish to anglers when they were such a problem? UDWR staff looked at each part of the issue and found creative solutions.
The first solution was stocking predators that cannot reproduce, such as sterile walleye and hybrid striped bass (known as ‘wipers’). Stocking sterile predators allows UDWR to control the number of large mouths in the reservoir because all fish in the reservoir were put there by UDWR, not from reproduction. Knowing the number of predators in the reservoir allows UDWR to stock enough trout for predator consumption AND angler opportunity.
But sterile predators are still predators, so those hungry mouths could still escape downstream and eat native fish. The second solution was keeping predators in the reservoir by screening all water leaving the reservoir, thus allowing water to reach the Green River, but not fish. A screen downstream of the reservoir allows UDWR to stock predatory fish in the reservoir without causing impacts to native species in the Green River.
With these solutions planned, UDWR aquatics staff oversaw a complete transformation of the Red Fleet fishery. In 2015, UDWR removed all fertile walleye and other fish from the reservoir. Based on angler input, UDWR subsequently stocked sterile walleye, wipers, largemouth bass, yellow perch, black crappie, trout, and fathead minnow. To complete the project, UDWR and the Recovery Program funded and built a screen to keep these fish from reaching the Green River.
Today, anglers can cast a hook and line for many desirable species in Red Fleet Reservoir, including large wipers. Simultaneously, predator escapement from Red Fleet Reservoir has been stopped. Using hard work, clear communication, and collaboration, Northeastern Region aquatic managers were able to solve a complex problem with multiple goals. This solution exemplifies the dual goals of the Recovery Program’s nonnative fish management actions – provide exciting angling opportunities in reservoirs while supporting endangered fish recovery in rivers. Great work UDWR staff in the Northeastern Region!