If you catch a greenback cutthroat trout, you are extremely lucky and you were probably in Colorado. An exhaustive study revealed that the greenback cutthroat trout’s last surviving wild population lives in just one Colorado stream. That discredits previous reports that five separate wild populations exist, making it an even rarer fish than before.
The greenback cutthroat trout is only known to occupy about 1 percent of its historical range. It is currently listed as threatened under the Endangered Species Act and it was even believed to be extinct by the 1930s. However, in 1957 a population was discovered in the Rocky Mountain National Park’s Big Thompson River, a tributary of the South Platte.
Researchers with the University of Colorado found that the only true population of greenback cutthroat trout survives today in Bear Creek, a small tributary of the Arkansas River west of Colorado Springs. The greenbacks, native to the South Platte, were likely stocked in Bear Creek in the early 1880s by a hotelier seeking to promote a route for tourists up Pikes Peak.
The study, published in the September 24 Journal of Molecular Ecology, “analyzed DNA extracted from wild trout and from museum specimens collected from sites around Colorado and New Mexico as far back as 1857. Researchers used the genetic data from the museum samples as a baseline for understanding the current distribution of Colorado’s cutthroat trout,” a release announced the sites involved in the study. DNA was sampled from cutthroat specimens pickled in ethanol for 150 years and more than 40,000 historic stocking records were cross-referenced, according to the New York Times.
“We’ve known for some time that the trout in Bear Creek were unique,” said Doug Krieger, senior aquatic biologist for Colorado Parks and Wildlife and the Greenback Cutthroat Trout Recovery Team leader. “But we didn’t realize they were the only surviving greenback population.”
This research will spark a revaluation of the greenback recovery program led by the U.S. Fish and Wildlife Service and Colorado’s Greenback Cutthroat Trout Recovery Program. The taxonomy and status of the species must be reevaluated to determine whether adjustments to its status and current protection are needed.