JACKSON, Wyo. — The Wyoming Game and Fish Department (WGFD) is testing out a new way of eradicating brook trout in Game Creek to allow native cutthroat trout to thrive.
Scientists with WGFD last week introduced the Trojan male brook trout, which only produces male offspring, into Game Creek in the hopes of causing the eventual die-off of brook trout there.
Wednesday, July 17 marked the first time the Trojan brook trout, which carries two Y chromosomes instead of the usual male X and Y chromosomes, has been introduced in Wyoming. A total of 3,600 of these fish were introduced into Game Creek. More Trojan brook trout were also stocked into two streams in Cody that day.
Fish from Game Creek make their way into nearby Flat Creek, and WGFD hopes that eradicating brook trout in Game Creek will put an end to this source of brook trout for Flat Creek, and in turn for the upper Snake River drainage.
“We have lots of sources of brook trout, but it’s one, and it’s one that we have an opportunity to do something about,” Diana Miller, Game and Fish fisheries biologist in the Jackson Region, told Buckrail. “We know how important our cutthroat fishery is in Flat Creek so we want to protect that.”
Brook trout are native to the East Coast, and were first introduced into Game and Flat creeks by WGFD in the 1950s to provide more options for fishing. That stocking continued into the 1960s and 1970s at what Miller estimates was a rate of seven cutthroat to one brook trout. But what WGFD didn’t predict was that brook trout would rapidly outcompete the native cutthroat, so that by the 1980s brook trout had taken over Game Creek.
Since then, WGFD has been making an effort to get the brook trout out of Game Creek, mainly by electrofishing, or stunning fish before capturing them with nets.
With the introduction of the Trojan, or “YY,” brook trout, WGFD aims to have only male brook trout in Game Creek within 10 years, and hopefully sooner, Miller says. Once there are no more females to breed with, the brook trout population will die out.
This effort will involve restocking Game Creek with more YY brook trout every year, according to Miller. And it will happen in conjunction with ongoing electrofishing.
“We’re helping out still,” Miller says. “It’s not like we can just walk away. But we’ll know which ones are wild and which ones are Trojan and they’ll stay in and we’ll remove the wild ones.”
The introduced YY brook trout have been marked by removing their adipose fins, the fins on their backs closest to their tails, so that scientists can distinguish them from the other brook trout in the creek.
“This is a huge step for our long-term goals in Game Creek,” Miller said in a statement.
