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DWR Postpones Rotenone Treatment at Yuba Reservoir

Yuba Reservoir
Yuba Reservoir - has become overrun with Northern Pike

Stocking sterile northern pike might be the answer

Nephi -- Despite intense management over the past five years, Yuba Reservoir is still not living up to its potential as a fishery. The reservoir in north-central Utah faces two challenges: northern pike that have invaded the reservoir from upstream water sources and low water levels that have prevented perch and walleye from successfully spawning in the spring. When perch and walleye are produced, the ravenous pike eat many of them.

At one time, Yuba offered some of Utah’s best yellow perch and walleye fishing. Is there a way to bring the fishery back?

With the help of a 28-person working group, biologists with the Division of Wildlife Resources drafted a management plan in 2013. Using rotenone to remove all of the fish in the reservoir, and then restocking it with fish, was one way the group suggested to bring the reservoir’s fishery back. The biologists went to work, drafting a rotenone treatment plan and finalizing an Environmental Assessment that’s required before chemical treatment can occur.

“During the process,” says Chris Crockett, regional aquatic manager for the DWR, “we discovered some challenges that will likely reduce the chance a treatment effort is successful.”

The biologists discovered three challenges:

Challenge 1 – Northern pike in adjacent and connected waters

The number of northern pike is spreading in numerous tributaries and irrigation canals that are connected to or feed into Yuba.

“During surveys,” he says, “we discovered that northern pike are more widespread in the Sevier River system, which flows into Yuba, than was previously known. They’re established throughout the Sevier River system and are commonly caught at DMAD Reservoir near Delta.”

Crockett says successfully treating all of the connected waters isn’t feasible. “Unless northern pike are completely removed from all of the connected waters,” he says, “the odds fertile northern pike make their way back into Yuba are extremely high.”

Challenge 2 – Lack of a sterile replacement for northern pike

One way to combat a future invasion of fertile northern pike is to chemically treat Yuba and then place sterile northern pike (pike that can’t reproduce) in the reservoir after the treatment. Even if fertile northern pike made their way to the reservoir, competing with the sterile northern pike for food and other resources might make it difficult for the fertile pike to gain a foothold.

Crockett says DWR biologists and fish culture personnel are developing techniques to produce sterile northern pike. But producing and stocking the fish is still a few years away.

“I’m excited about the possibilities sterile northern pike provide,” Crockett says. “Because they can’t reproduce, we can closely control their numbers and maintain a better balance between the pike and the fish the pike prey on. Also, because they can’t reproduce, sterile northern pike spend all of their time feeding, which allows them to grow to a larger size faster. They have the potential to provide anglers at Yuba with a fast-growing trophy opportunity.”

Crockett says biologists might also re-evaluate other species that might do well in low water conditions. Species that can quickly take advantage of brief windows of higher water might also be considered.

Challenge 3 – Reservoir drawdowns

As it is everywhere, water is a precious commodity in north-central Utah. And there isn’t always enough of it to meet everyone’s needs.

In recent years, the water level at Yuba Reservoir has dropped more than 35 feet each year, leaving the reservoir between 5 and 10 percent full before winter and spring precipitation replenishes the supply. Then, the cycle starts over again.

“Seasonal fluctuations make it difficult to maintain a stable fishery,” Crockett says. “Low water levels reduce habitat and water quality for all of the fish species. In the case of perch and walleye, declining water levels during the spring and summer severely limit their ability to reproduce.”

Again, sterile northern pike might be the answer.  “Introducing sterile northern pike,” he says, “would help protect perch and walleye by allowing us to better control the number of pike in the reservoir. Even if perch and walleye have a poor spawn, keeping the number of predators down should help the number of perch and walleye increase.”

Yuba Reservoir Working Group

The 28-person Yuba Reservoir Working Group includes representatives from fishing groups, natural resources agencies, the local fishing industry and local water owners. The group was instrumental in helping the DWR draft the 2013 management plan.

“We’re going to reconvene the working group later this year,” Crockett says, “and get their help in revising the plan. With their help, I’m confident we can draft a plan that gives us the best chance possible to make Yuba Reservoir a great fishing water again.”

In the meantime, a rotenone treatment at Yuba—which would have cost anglers more than $500,000—has been put on hold.

“We can’t invest that kind of money and effort without considering all of the challenges the reservoir faces,” Crockett says. “We need to make sure we explore all of our options. Whatever we do needs to work.”

If you have questions about fishing at Yuba Reservoir, call the DWR’s Central Region office at 801-491-5678.