The Wyoming Game and Fish Department successfully completed a rotenone project at Saratoga Lake to remove illegally-stocked yellow perch.
In mid-September, department personnel applied 14,000 pounds of rotenone to Saratoga Lake to kill illegally introduced yellow perch. In October, fisheries biologists returned to the lake for two separate sampling events to see if any fish remained. After a total of 10 days without a single fish caught in numerous gill nets, biologists deemed the project complete.
“It went well. We did not catch any fish, which is awesome,” said Laramie Region Fisheries Supervisor Bobby Compton. “It means the project was a success.” Compton said it also means the department won’t have to repeat the project, which cost 1,150 man hours and nearly $140,000.
In addition to eliminating the yellow perch, thousands of white suckers were also removed from the lake. For three days following the application of the rotenone, Game and Fish Department personnel cleaned up dead fish from the shore of the lake. “It was a huge effort to pick up all the dead fish and dispose of them. We estimate there were more than 10,000 fish, and about 70% were white suckers, with most of them 15 to 20 inches,” Compton said. “Getting rid of the sucker population in Saratoga Lake is going to vastly improve the trout fishery for the near future. That was a lot of suckers taking up food that could have gone to trout.”
Another benefit of the project is the removal of invasive brook stickleback, a small minnow native to central North America. Brook stickleback are spread as a result of bait introductions, accidental introductions with aquaculture species and through water currents.
Unfortunately, trout were also victims of the rotenone, representing 20% of the dead fish. Yellow perch made up the other 10%. “There were a lot more perch than we anticipated being in the lake, and the population was growing,” Compton said.
Compton said the department has plans to address the white suckers and brook stickleback, which come into the lake from the North Platte River. “We’re looking at a screening solution to keep them from returning to the lake,” Compton said. “We hope to have a fish screen in place sometime this winter before the lake is refilled.” While screening the inlet from the North Platte River won’t guarantee the elimination of undesirable species, it should impede their access and considerably slow their population growth.
The Game and Fish Department plans to restock the lake with trout in the spring of 2023. The goal is to stock 6,500 catchable (nine-inch) rainbow trout, 1,500 seven-inch brown trout, and 2,500 fingerling tiger trout. At three to six inches of growth per year, the brown trout will grow to catchable size by fall of 2023. There are also plans to add some larger broodstock trout in the fall of 2023 prior to the ice fishing derby.
Compton expressed his gratitude to the Town of Saratoga, the lakeside homeowners, the Bureau of Land Management, and the entire community. “They were very supportive throughout the entire process. We could not have done this project without their cooperation,” he said.
The Game and Fish Department encourages anyone with information regarding this illegal introduction of yellow perch to contact the Department (1-877-WGFD-TIP). Identities can remain confidential.
