Grand Rivers: Challenges and Opportunities in Native Fish Conservation in the Upper Colorado River Basin (Symposium/2024 Area Report)

Authors: Dave Speas

Year: 2024

Abstract

The Upper Colorado River Basin is the primary water source for millions of users in the Southwestern United States for municipal, industrial, agricultural, cultural, and recreational purposes as well as hydropower generation. The native fish fauna of the basin has long suffered the ill effects of river regulation and depletion, invasive species introductions, and most recently, climate change. Four species of fish—Humpback Chub Gila cypha, Razorback Sucker Xyrauchen texanus, Colorado Pikeminnow Ptychocheilus lucius and Bonytail G. elegans—are currently protected under the Endangered Species Act, and Flannelmouth Sucker Catostomus latippinis, Bluehead Sucker C. discobolus and Roundtail Chub G. robusta are the subject of conservation programs managed mostly by state fish and wildlife agencies as part of the “three species” conservation agreement. Endangered fish recovery programs in the Upper Colorado and San Juan rivers were established in 1988 and 1992, respectively, with the twin goals of endangered fish recovery while water development continues within the bounds of state and federal legal compacts and regulations. As the struggle to recover endangered fish and protect sensitive species continues, managers and scientists continue to seek out and implement innovative and novel approaches to recovery and conservation. To these ends, recent and noteworthy examples covered in this symposium/area report focus on the following topics: • Use of dam operations—long viewed as a primary source of jeopardy to native fauna—helps provide riverine-floodplain connection during periods of larval razorback sucker emergence and drift. • Understanding fish behavior in the presence of in-stream barriers and an emergent waterfall on the San Juan River helps identify passage alternatives. • Innovative fish screen design and materials provide endangered fish safe routes around canal intakes. • Finding a path to recovery for Bonytail through adaptive rearing and stocking approaches, including use of floodplain wetlands. • An alternative to mechanical removal of non-native fish using strategically timed dam releases to disadvantage invasive smallmouth bass. • Use of ancillary PIT detection data enhances active mark/recapture population estimates of endangered fish. • Hands-on endangered fish propagation comes to high school classrooms in Colorado and beyond, inspiring a generation of future fish biologists. While much of this work has been aimed at endangered fish recovery, it is expected that these efforts will benefit non-listed species as well and help preserve the ecological integrity of the river systems as a whole.