For more than 20 years, state and federal fisheries managers have been stocking truckloads of trout in an effort to save Colorado’s endangered greenback cutthroat. And it all seemed well worth it last year, when the Colorado Division of Wildlife reached its goal of 20 self-sustaining populations, positioning the fish for delisting. But that’s all changed now that a University of Colorado at Boulder study shows that biologists heading the greenback’s recovery have been inadvertently stocking not greenbacks but Colorado River cutthroats.

In Molecular Ecology, the study’s authors write: “Our results suggest greenback cutthroat trout within its native range is at a higher risk of extinction than ever before despite conservation activities spanning more than two decades.”

Read the report here.