 In 2012, a genetic study that compared DNA samples both from modern populations and historical samples dating back to the 19th century revealed that the only remaining population of pure greenback cutthroat trout is found in a stretch of Bear Creek, a tributary of the Arkansas River.Many of the populations previously identified as greenback cutthroat were actually of the similar Colorado River and Rio Grande cutthroat subspecies.The study also cleared up the confusion Hammond's labeling had created.