The native fish populations of the Upper Colorado River Basin are one of the least protected yet most unique groups of fish in North America. The Colorado River basin contains a higher percentage of endemic species than any other basin in North America.
Unfortunately, the future of many of these fishes is in jeopardy. Already, four of the 14 native Upper Colorado River Basin fishes have been listed as endangered under the Endangered Species Act, while others have been designated as sensitive due to their declining status.
The Colorado River cutthroat trout is designated as a species of special concern by several states and federal agencies. Today, only 14% of its historic range is currently occupied and only 8% of the historic range is occupied by unhybridized or ecologically significant populations. Extensive introductions of non-native trout over the last century, plus habitat degradation from human activities such as water use, development, habitat overuse and road building have fragmented and reduced populations.
These human activities have also disturbed populations of the sensitive warmwater fishes. Historically, these fishes were found in the mainstems and many medium-to-large tributaries within the Upper Colorado River Basin. However, water development projects, land use management and non-native species invasions have extirpated these fishes from approximately half of their historic range. Today, the flannelmouth sucker, bluehead sucker and roundtail chub occupy just 45%, 50% and 45% of their historical habitat, respectively.
The goal of NFWF's Upper Colorado River Native Fishes Conservation Program is to stabilize and increase the populations of four Colorado River native fishes -- Colorado River cutthroat trout, bluehead and flannelmouth sucker, and roundtail chub -- in order to prevent federal listing as threatened or endangered. It focuses on connecting headwater streams where native Colorado River cutthroat trout occur in sympatry or close proximity with downstream populations of native warmwater fishes. By focusing on areas that have the potential to boost multiple species populations, the initiative increases the conservation benefit of each dollar spent.
Key conservation strategies for this program include:
- Managing non-native fishes, such as rainbow trout and white sucker, which hybridize with and prey upon native fishes;
- Restoring natural water flow regimes by removing dams, or operating them to mimic natural stream flow, or by installing fish passage structures;
- Conserving water to maintain adequate stream flows and improving water quality through efficient irrigation technology and other strategies;
- Reducing the impacts of land disturbance and erosion by implementing stormwater runoff and road construction and maintenance best management practices;
- Maintaining water quality through proper treatment of energy development waste; and
- Mitigating the impacts of climate change through strategic planning.
Applicants should identify how their proposed activities fit within the framework outlined in the Upper Colorado River Native Fishes Business Plan and, specifically refer to the map.
Since the beginning of NFWF’s involvement in the region, native fish populations have experienced substantial increases: 3,900 Colorado Cutthroat trout, 4,600 bluehead suckers, 4,600 flannelmouth suckers and 4,600 roundtail chub.