Fish
There are about 28,000 fish species in the world, all of which are aquatic, cold-blooded, covered in scales and breathe through gills. Fish populations are in perilous decline across the planet, primarily from overfishing and habitat loss and degradation. Introduction of non-native species is also a major threat — the yellowfin cutthroat trout, once plentiful in Colorado’s high country, went extinct with the introduction of rainbow trout to its native habitat.
Bonytail
Threats to the bonytail include flow regulation, habitat loss and alteration, competition with and/or predation by exotic fishes, and water pollution in the Colorado River Basin. Selenium, a heavy metal found in effluent from uranium mines may bioaccumulate in the fish, impacting species higher in the food chain like river otters and bald eagles.
Colorado Pikeminnow
Similar to salmon, Colorado pikeminnow can migrate more than 200 miles to spawn. They are threatened by flow regulation, habitat loss and alteration, and water pollution in the Colorado River Basin.
Colorado River Cutthroat Trout
Once prevalent in headwater streams throughout the Colorado River system, the Colorado River cutthroat trout now inhabits only a few upper reaches in northwestern Colorado and southwestern Wyoming. All three of our region’s surviving native cutthroat trout species are threatened with extinction.
Greenback Cutthroat Trout
The Greenback cutthroat trout survives only in small parts of the Arkansas and South Platte River systems. All three of our region’s surviving native cutthroat trout species are threatened with extinction; no more than 17 populations of pure Greenback are thought to survive.
Humpback Chub
Historically, the humpback chub inhabited canyons of the Colorado River and four of its tributaries: the Green, Yampa, White and Little Colorado rivers. Now, there are only two populations in the Upper Colorado River drainage. It is threatened by flow regulation, habitat loss and alteration, competition with and/or predation by exotic fishes, and water pollution.
Razorback Sucker
The razorback sucker is an extremely rare, large-river fish found only in the Colorado River basin. It is threatened by flow regulation, habitat loss and alteration, competition with and/or predation by exotic fishes, and water pollution.
Rio Grande Cutthroat Trout
Rio Grande cutthroat trout require clear and cold water, naturally-fluctuating stream flows, low levels of sediment, well-distributed pools, stable streambanks, and abundant stream cover. All three of our region’s surviving native cutthroat trout species are threatened with extinction.
Yellowfin Cutthroat Trout
The Yellowfin cutthroat trout, first identified in Colorado in 1891, is now extinct. Originally found near the headwaters of Colorado’s Arkansas River, the Yellowfin cutthroat trout was wiped out when rainbow trout (Oncorhynchus mykiss) were introduced into its Twin Lakes home.