Game and Fish wrestles with how to handle illegal introduction of fish in Wyoming waters

SHERIDAN — Fish that are illegally introduced to non-native bodies of water can cause lasting impacts to the water’s ecosystem and a community’s economy, according to Wyoming Game and Fish officials.

An illegal introduction occurs when someone moves a fish from one body of water to another, Wyoming Game and Fish Department Chief of Fisheries Alan Osterland told the Wyoming Legislature’s Joint Travel, Recreation, Wildlife and Cultural Resources Committee earlier this week.

Osterland said fishermen may have grown up catching a specific fish and now want an opportunity to catch it closer to home. He added a private citizen may not fully recognize the impacts that moving a fish can have.

“Illegal introductions of fish into waters of Wyoming and the west can (have), and has been, a significant impact to both the local economies in some instances, and the ecology of the water bodies that they come into,” Osterland said.

Walleye and lake trout — two apex predators in the fishery world — are present in Lake DeSmet. WGFD stocks the lake with smaller trout to create a recreational fishery. Because Lake DeSmet is a cold water fishery, walleye wouldn’t be expected to do well in the environment, but Osterland said the species is doing well and reproducing.

Another example came in 2021, when perch were discovered in Saratoga Lake in Carbon County. The 100-acre reservoir typically houses a trout fishery, but there aren’t any perch in that surrounding area.

“To have perch in Saratoga Lake was really concerning to us,” Osterland said.

Should the perch have entered the nearby North Platte River system, it could have impacted walleye fisheries and trout fisheries throughout the system, Osterland said.

Ultimately, WGFD officials decided to treat the lake with a chemical that inhibits oxygen intake for gilled animals, and every fish in the lake was removed.

That project cost WGFD $140,000 for supplies and 1,150 man hours to distribute the chemical, cleaning up the dead fish, gathering additional samples and restarting the fishery the following year.

“A lot of sportsmen’s hours went into that treatment there, and it removed a lot of the local economy’s dollars that would be coming in,” Osterland said.

Goldfish are another species that can find their way into Wyoming’s waters. The household pets can have a significant impact by consuming the system’s nutrients and making the water muddy.

Walleye have been present in the Buffalo Bill Reservoir, in Park County, since 2008, and WGFD officials have worked since then to attempt to suppress the walleye population and maintain a healthy trout fishery.

“We could be doing that forever just because somebody along the line thought that it was a good idea to throw walleye in there so that they may be able to catch those walleye in a local area,” Osterland said.

Osterland explained Wyoming already has a strong statute making it illegal to introduce fish or eggs into any public water without WGFD permission. An offense is punishable by up to one year in jail or $10,000; offenders could also have their fishing privileges revoked for the rest of their lives.

Those cases, though, can be hard to prosecute, so Wyoming and other western states use informational campaigns to tell residents why moving fish can have serious impacts.

At this point, the Joint Travel, Recreation, Wildlife and Cultural Resources Committee is not considering any legislative changes to further combat illegal fish introductions.