Real Greenbacks Identified Just in Time

The fly fishing world is buzzing after a scientific study released three days ago explained that the trout which fisheries biologists in Colorado had thought were native greenback trout really aren’t; however a small population of “real” greenbacks—thought to be the last in the world—has been identified in a small creek near Colorado Springs.

It’s a fascinating story of science and history, with huge ramifications on how wild and native trout will be managed in the future.

Dr. Jessica Metcalf and her colleagues from the University of Colorado used highly sensitive DNA analysis to compare samples of cutthroat trout from different drainages in Colorado today with the DNA from fish that were collected 150 years ago, preserved in ethanol, and stored in museums ever since. The DNA matched the historic South Platte River greenback species with a small population of this trout now found in Bear Creek, part of the Arkansas River system. Interestingly, those fish are descendents of greenbacks that had been stocked in that creek over 100 years ago, and have managed to persist as the only wild greenback trout population in Colorado.

The greenback—Colorado’s state fish—was thought to be extinct in the 1930s, but then was “rediscovered” in 1953. Within the past 20 years massive efforts from state and federal agencies have been poured into reintroducing greenbacks into their native rivers (like the South Platte drainage). Problem is, we now know that these fish aren’t “true” greenbacks, rather a strain of Colorado River cutthroats from the west side of the Continental Divide (it isn’t a matter of fault; the best science at the time indicated that these fish were indeed greenbacks).

The good news is that the real greenbacks have been found—they have survived in one small, isolated creek for years as the only population that saved the species from extinction. Some of those fish have now been moved to hatcheries, where they will become brood stock that leads the future efforts to truly restore greenbacks in their native range.

The fact that this has all been sorted out at all was a one-in-a-million opportunity. Consider the fact that between the 1880s and 1953, 750 million trout were transplanted and stocked in the state of Colorado alone. Today, most trout fisheries are hodge-podge mixes of non-native species—which is fine in the context of recreational fishing. It never will be the same as it once was. That’s just reality.

But in some cases, we do have opportunities to untangle the genetic webs that have been woven, and restore native trout in their historic ranges—ensuring that what was, will still be there for future generations to appreciate.

This study of the greenback trout in Colorado may offer the most significant findings and ultimately impact on native trout species in our lifetimes.

For more information, visit theUniversity of Colorado Research Story, the Colarado Parks and Wildlife’s Cutthroat Trout Conservation page or the Greenback Cutthroat Trout Recovery Team page.

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