Solving the Genetic Mysteries of Colorado’s Native Trout—and Protecting Our Local Subspecies
Enjoy solving riddles? Try this one on for size: The beautiful greenback cutthroat trout, native to the eastern slope of Colorado, is declared extinct in 1937. In the 1950s, it is rediscovered. By the 2000s, it is found across the western slope. How?
In recent years, unraveling the mystery of the greenback cutthroat sent state biologists and university researchers into a tailspin of confusion, which spurred intense DNA investigation of this iconic subspecies of Colorado’s native trout. The answer to the riddle, they came to find out, involved a case of mistaken identity and several unfortunate—though well-intended—pioneer stocking operations stretching as far back as the 1870s. Nope, those fish didn’t leap across the Continental Divide on their own.
A Statewide Soup of Genetics
Miners, settlers, homesteaders, ranchers, and families: They came to Colorado in droves in the late 1800s, and they needed resources to eat, to grow, and to mine. In settling the west, they fished the streams and lakes without restraint, dewatered rivers, and poisoned many of the remaining waters with mining and industrial waste. By the turn of the 20th century both the state and federal governments, along with some enterprising private residents, had set up hatcheries in various locations with the intention of producing massive numbers of fish to replenish the waters people had plundered—but without regard to the fishes’ native ranges. It is estimated that tens of millions of trout were raised and scattered across Colorado by the early 1900s, resulting in a statewide soup of cutthroat genetics ladled on both sides of the Divide. Two of the state’s cutthroat subspecies—greenback (native to the east) and Colorado River (native to the west)—were mixed and mingled in multiple watersheds for the perceived public good.
A state operation at Trapper’s Lake, deep in the Flat Tops north of Glenwood Canyon, collected and distributed eggs from cutthroats in the upper White River watershed. Further west, a federal hatchery cultivated millions more from wild trout local to the Grand Mesa. Fish from these eggs were relocated up and down the eastern slope, and their descendants still thrive along the Front Range today.
Prior to this government work and widespread transplantation of trout, early settlers had been conducting their own fish-stocking initiatives. In 1873, in hopes of opening an inn along Bear Creek to capitalize on the tourists climbing Pike’s Peak, a Mr. J.C. Jones is believed to have stocked its waters with genetically pure greenback cutthroats procured from their native habitat in the South Platte River watershed. In doing so, he may have inadvertently saved the greenback subspecies from complete extinction, as it later disappeared from its native range.
Now back to the riddle. How was it that greenbacks could be declared extinct and then rediscovered in such an unusual way? The answer is simple. For years after the greenback was added to the Endangered Species list in 1973, well-meaning state officials had been attempting to increase their numbers by replenishing eastern slope waters with what they believed were greenbacks from a population in the South Platte River valley—but those “greenbacks” weren’t really greenbacks at all. They turned out to be an entirely different subspecies altogether. So, the riddle is a bit of a trick.
In the early 2000s, innovative DNA research techniques used at the University of Colorado (CU) Boulder revealed that the “greenbacks” in the South Platte watershed were actually Colorado River cutthroats, native to the western slope, which had been transplanted to the South Platte during early stocking operations at the turn of the 20th century. Unbeknownst to state officials, the unusual-looking cutthroats in Bear Creek were the one true population of greenbacks, and instead they had focused on the misidentified “greenback” populations elsewhere. Genetic investigations involving the use of trout specimens originally collected by 19th century explorers and preserved in museums across the country later confirmed that those Bear Creek beauties are indeed the only real deal.
Indigenous Trout in the Roaring Fork Valley
Today, extensive DNA testing at the state and university level has helped clear up numerous cases of mistaken identity of our beloved cutthroats and determined that each of the six major watersheds in the state had its own genetically unique cutthroat. Here in the valley, officials are currently working to protect one of two previously unrecognized cutthroat subspecies currently identified as the “green-lineage” cutthroat. Efforts are underway to have them taxonomically characterized and named. Colorado Parks and Wildlife Aquatic Biologist Kendall Bakich, based in Glenwood Springs, is working with her team to ensure that these precious local treasures are protected here.
“In the Roaring Fork Valley we have two known genetically pure green-lineage populations, and they’re the focus of my conservation work right now,” she reports. “They’re vulnerable. We need to find as many as we can, protect them where they are, and then try to expand them.”
Currently, these two populations exist in Hunter Creek near Aspen and Cunningham Creek in the upper Fryingpan River watershed. Their biggest threat? Invasion by other trout species.
“Our primary objective is to protect the indigenous fish in their natural habitat, especially from the invasion of non-natives like rainbow, brown, and brook trout,” Bakich notes. “Most of the time the cutthroats live in pretty good conditions up higher in the watershed, but unfortunately the natural barriers that once protected them from other species in these two streams have both failed.”
Bakich says that brook trout, widely introduced from the eastern U.S. for sport fishing long ago, are especially aggressive predators that claim essential resources from the indigenous cutthroats. The only way to ensure that the cutthroats can continue to live in their native habitat is to physically remove all the invasive trout.
“Of course, that doesn’t mean we can go out there and physically catch all the brook trout in all waters,” Bakich adds with a laugh. “That would be impossible. What we can do is chemical reclamation in streams or lakes that have the appropriate environmental conditions—both for cutthroat trout and efficacy of the chemical. Typically we need a large group of state-certified personnel—over 50 people—to do the project. We use a natural plant-derived chemical to remove the brook trout over the course of a day or two, and then it detoxifies and is gone from the water.”
Much of these reclamation projects’ success rides on public awareness and community support, Bakich says. She has made great efforts to inform locals of her team’s conservation work, including a recent Naturalist Nights presentation hosted by Wilderness Workshop, Roaring Fork Audubon, and the Aspen Center for Environmental Studies.
“We need community buy-in to make this work,” she adds. “We want to make sure that people understand why, and how, we do this. These are big projects, especially in a large watershed like Hunter Creek.”
This month, Bakich is beginning field season with her team and will be working frequently in the Hunter and Cunningham creek areas, but she welcomes community feedback at any time.
“If people want to talk,” she says, “I’m taking input.”
The author wishes to extend sincere thanks to Kendall Bakich for her generous assistance with article research.