HOT SULPHUR SPRINGS, Colo. — Using a strategy right out of "Jurassic Park," Colorado Parks and Wildlife (CPW) is making a "historic" effort to eradicate a non-native species of fish that's been threatening Colorado's cutthroat trout population.
CPW said in a release that on Sept. 17, they stocked 480 Trojan male brook trout, also known as YY brook trout, into Bobtail and Steelman creeks in Grand County, south of Hot Sulphur Springs.
The fish are called YY because they have two Y chromosomes, unlike wild males that have an X and a Y chromosome. YY trout are stocked into wild brook trout populations and reproduce with the wild fish, producing only male offspring.
Without a reproducing population, CPW said, the brook trout will eventually die out, allowing for the native cutthroat to be restored.
“This is a pretty historic moment for Colorado and native cutthroat trout restoration across the state,” said CPW aquatic biologist Jon Ewert. “This is a combination of both the hard work and dedication of CPW biologists current and retired.”
It's considered historic because it's never been done before in Colorado, but CPW aquatics research section chief George Schisler said it won't be the last time.
"This is just the first of many for Colorado," he said.
CPW said that in 2010, a fish survey in the headwaters of the Williams Fork River revealed an "alarming" number of non-native brook trout. It's not known when brook trout invaded those waters, but it was evident the thriving brook trout had nearly decimated the native cutthroat population over time.
Cutthroat trout in the Bobtail and Steelman creeks are some of the highest-valued native cutthroat populations in the headwaters of the Colorado River basin, CPW said. They are considered a species of special concern in Colorado.
Efforts to restore them have been successful, increasing the number of cutthroat trout in the two creeks from 123 in 2011 to more than 1,400 today.
Anyone who's seen "Jurassic Park" or read the book knows the all-female dinosaur strategy didn't work out. But CPW expects this real-world method to have a very different result.
The agency said it will continue to stock both streams with YY brook trout over the next several years to sustain the number of Trojan males in the population, eliminating the production of female brook trout in the creeks.
