Greenback Cutthroat Trout, Imperiled State Fish, Stocked in Lake as Part of Recovery
Last week, biologists released 1,200 greenback cutthroat trout into Zimmerman Lake, about an hour and a half west of Fort Collins. The four-inch-long, one-year-old fish were raised in hatcheries and are the descendants of the last known wild greenback population, which lives in Bear Creek outside Colorado Springs. The release was the latest effort in a decades-long journey to save the fish from extinction -- a journey that has included several rounds of setbacks, successes and scientific breakthroughs.
We wrote about the greenbacks' saga in this week's cover story, "One Fish, Two Fish." Thought extinct in the 1930s, the colorful trout were rediscovered in the 1950s -- or so biologists thought. In the 1970s, the greenbacks were included on the first-ever Endangered Species List, and state and federal biologists began efforts to conserve the species and increase its ranks through breeding and stocking.
But a 2007 University of Colorado study cast doubt on whether the greenbacks they were saving were greenbacks at all. A follow-up study published in 2012 confirmed that the fish they'd spent so much time on was actually a different subspecies of cutthroat trout.
Researchers concluded that the last known greenbacks live only in a four-mile stretch of shallow Bear Creek, and counts showed that there were only about 700 of them left. So the biologists started over again, transporting some of the Bear Creek fish to hatcheries and breeding them with the idea of releasing their offspring into the wild.
The first release happened on August 8 in Zimmerman Lake. The lake was rendered fishless to prepare for the greenbacks' arrival. If non-native species such as brook or rainbow trout encounter greenbacks, they'll replace them or breed with them, creating hybrid species. Therefore, it's important that the greenbacks not have any competition.
Courtesy of Doug Krieger Biologists put greenbacks in buckets at Zimmerman Lake.
Continue for more on the release of the greenbacks into Zimmerman Lake.