Walleye Stocked Illegally in Echo Reservoir


Walleye have been placed illegally in Echo Reservoir. DWR biologists have some concerns about how the illegally introduced fish might affect fishing for trout and other fish in the reservoir.

DWR Press Release

Coalville – Walleye have been stocked illegally in Echo Reservoir.

Staff with the Division of Wildlife Resources learned about the illegal stocking through a fishing report posted recently on social media. After receiving the tip, DWR biologists conducted a netting survey. The survey turned up 29 young walleye at the reservoir northwest of Coalville.

Craig Walker, warm water sport fisheries coordinator for the DWR, says it’s always disappointing to learn that a fish has been placed in a water illegally. “While some anglers might think this illegal introduction is going to provide another great opportunity for walleye fishing along the Wasatch Front,” he says, “not so fast.”

Walker says walleye provide excellent fishing in many Utah waters, including Starvation Reservoir, Willard Bay Reservoir, Utah Lake and Lake Powell. “But for every good walleye fishery in the state,” he says, “there are several other waters, like Echo Reservoir, where walleye simply don’t belong.”

Walker says walleye, which are not native to the West, possess two traits that make them a problem in many Utah waters. First, they feed almost entirely on other fish. Second, they are prolific breeders; they can establish a large population in a short period of time.

These two traits make walleye ill-fitted for many western reservoirs; they can decimate native fish populations, outgrow their prey base and destroy existing sport fisheries by preying on other valuable species, including rainbow trout, kokanee salmon and smallmouth bass.

Walker says he can understand what drives these illegal introductions.  “Among North American fishes,” he says, “a dinner of walleye fillets is second to none.”

In addition, Walker says, many anglers like the challenge of catching walleye.

Why illegal fish stocking is a bad idea

One of the problems with anglers tinkering with fish communities, like the one at Echo Reservoir, is the illegal stocking is not well thought out.

Walker says reservoirs like Echo, which can fluctuate annually by 30 vertical feet due to irrigation draw-down, often lack the cover needed to the produce enough prey to sustain what could be an exploding walleye population.  The end result is often a reservoir filled with small, overabundant walleye and years of mediocre fishing.

Walker says the effects of this illegal fish introduction into Echo are unknown. “If the walleye numbers remain low,” he says, “they shouldn’t do much harm to the fishery. Unfortunately, there’s an abundance of spawning habitat in the reservoir, so it’s likely the walleye population will expand quickly.”

Walker says recent netting surveys have shown that Echo currently boasts a large yellow perch population, a favorite prey of walleye, so the walleye will likely have adequate food for at least the next few years.

“The problem is that walleye may do well in the short term in Echo Reservoir,” he says. “It may take years for the walleye to thin out their prey base and for the damage to be felt. This may be good in the short term, but it leaves a ticking time bomb that fishery managers will have to deal with. It’s one of the reasons fisheries managers have not considered introducing naturally reproducing walleye to Echo.”

Future for the reservoir

Despite the unknowns, Walker and other biologists with the DWR have put a multi-faceted adaptive plan in place, to try to make the best of the situation.

The first step is to stock larger rainbow trout. These larger rainbows should be big enough to avoid predation by walleye.

Next, says Walker, a catch-and-kill regulation will be put in place immediately. The regulation will require anglers to kill any walleye they catch.

“The catch-and-kill regulation is intended to remove as many walleye as possible until the next step of the strategy is implemented,” he says.

Third—and this is where things get interesting—in 2017, DWR will stock sterile walleye on top of the illegally introduced fertile walleye. Walker’s hope is that the sterile walleye will attempt to breed with the naturally reproducing walleye, effectively cancelling out their reproductive efforts and minimizing reproductive success of the population.

“This concept of mixing sterile walleye into a population, to hinder reproductive success, is called ‘swamping,’” Walker says. “We’re experimenting with it at Big Sand Wash Reservoir in northeastern Utah. And Colorado Parks and Wildlife is also experimenting with it at Rifle Gap Reservoir in Colorado.”

Walker says stocking sterile walleye, on top of fertile walleye that were illegally introduced, may sound counterintuitive. But he says it might allow biologists to manage walleye numbers in Echo Reservoir and prevent the species from overpopulating and outstripping its prey base. He adds that after a five-year period, once the potential benefits of the sterile walleye stockings have been realized, DWR biologists plan to revisit their strategy, adapting actions in the plan to maximize the benefits to anglers.

“While we hate illegal fish introductions,” Walker says, “we’re looking to use the one at Echo Reservoir as an opportunity to study our ability to manage and prevent more introductions in the future.”

Working with anglers

“I would much rather work with anglers than against them”, says Walker, pointing to the numerous introductions of new species the DWR has done over the past few years as part of angler-driven water management plans. Such plans have resulted in new and diverse fish communities at waters like Red Fleet Reservoir and Jordanelle Reservoir. Both reservoirs have been infused with new and different species with an eye on successful long term management.

“Red Fleet recently received introductions of wiper, black crappie, yellow perch, tiger trout, mountain whitefish and fathead minnow,” Walker says, “while Jordanelle Reservoir recently received introductions of tiger muskie, kokanee salmon and wiper.

“Where we can,” Walker says, “we’re trying to expand opportunities and meet the desires of anglers. We really want to provide anglers with the fishing opportunities they desire on waters that can support these populations.”

Although angler introductions of new fish species might be well intentioned, the impacts of many species illegally stocked into Utah’s existing fisheries can be devastating. Take Yuba Reservoir for example.

“The illegal introduction of northern pike has now made management of the fishery at Yuba nearly impossible,” he says. “In the case of Echo Reservoir, anglers need to realize that we can’t let angler desires prevail over sound fisheries management. Whenever a new species like walleye thrives, it’s often at the expense of fish—already in that body of water—that people enjoy catching. The selfish needs of a few anglers—stocking their fish of choice illegally—often results in the loss of a valuable resource for the majority of anglers.”

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