HomeOutdoorsNewsIllegally-Stocked Fish Forces Wyoming Officials to Kill All Marine Life in Saratoga Lake

Illegally-Stocked Fish Forces Wyoming Officials to Kill All Marine Life in Saratoga Lake

by Amy Myers
Photo by Linda Davidson/The Washington Post via Getty Images

After discovering invasive yellow perch in Wyoming’s Saratoga Lake, wildlife officials eliminated all fish to remove the illegally-stocked species. 

Initially, Wyoming Game and Fish began the project back in September. Once they realized that yellow perch had infiltrated the lake’s delicate ecosystem, they decided to use rotenone, an odorless, colorless broad-spectrum piscicide to kill off all the fish in the waterway. Rotenone naturally occurs in the roots of several plants, including the jicama root plant, and is a common choice for pesticides and piscicides. 

Weeks after implementing rotenone, officials continuously returned to Saratoga Lake to check on the progress of the elimination. Finally, in October, sampling events demonstrated empty gill nets across the entire lake for 10 consecutive days. As a result, experts deemed the project complete. In fact, Laramie Region Fisheries Supervisor Bobby Compton is quite happy with how the operation unfolded.

“It went well. We did not catch any fish, which is awesome,” said Laramie Region Fisheries Supervisor Bobby Compton in a statement. “It means the project was a success.”

Of course, yellow perch wasn’t the only fish that resided in Saratoga Lake, but in order to get rid of the invasive species, the state had no choice but to eliminate all scaly residents. Roughly 20 percent of the dead fish were trout while just 10 percent were yellow perch.

“There were a lot more perch than we anticipated being in the lake, and the population was growing,” Compton said.  

Wyoming Wildlife Officials Plan to Restock Fish-Less Lake With Trout Come Springtime

The silver lining of the mass elimination is that now officials can ensure a more biodiverse ecosystem under the surface of Saratoga Lake. According to Compton, the remaining fish that they pulled from the Wyoming waterway were all white suckers. Now, with a clean slate, they’ll be able to restock the lake with trout in the spring and restore balance to the submarine food chain.

“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.”

In the future, Wyoming Fish and Game department plans to implement a barrier to help keep out any unwanted species and protect the trout population.

“We’re looking at a screening solution to keep them from returning to the lake,” Compton shared. “We hope to have a fish screen in place sometime this winter before the lake is refilled.”