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TOWARD RANGE-WIDE INTEGRATION OF RECOVERY IMPLEMENTATION PROGRAMS FOR THE ENDANGERED FISHES OF THE COLORADO RIVER Robert Wigington and Dale Pontius Prepared for discussion purposes for the Colorado River Workshop. The paper is the work of the individual author and does not represent the opinion of Grand Canyon Trust or the Bureau of Reclamation. INTRODUCTION The Colorado River is home to some of the most unique fresh water fishes in the world. Four of these native "big river fishes" are now dangerously close to extinction - the Colorado squawfish, the humpback and bonytail chubs, and the razorback sucker. Historically, these four fishes were found in abundance throughout the Colorado River and its major tribu- taries, which are legally divided into Upper and Lower Basins at Lee Ferry on the Colorado River mainstem just below Glen Canyon Dam. ROBERT WIGINGTON is an in-house water attorney for The Nature Conservancy at its Western Regional Office in Boulder, CO. Western Regional Office The Nature Conservancy 2060 Broadway, Suite 230 Boulder, CO 80302 DALE PONTIUS is an experienced western water and natural resources attorney and is currently a consultant for The Nature Conservancy. 7990 E Snyder Rd, Apt #11202 Tucson, AZ 85750 Currently, the Colorado squawfish has been extirpated from the Lower Basin, except for any remnants of re- introduced, experimental populations, but natural populations still persist in the Upper Basin. The squawfish populations in the Yampa and Green Rivers of the Upper Basin have been greatly reduced but may be fairly stable. The bonytail is the rarest, with very few captures in the wild in the last decade. The hump- back chub, which was not described as a separate species until 1946, may be most numerous in the Lower Basin, in and near the confluence of the Colorado and Little Colorado Rivers in the Grand Canyon. Humpback populations persist in the Upper Basin in the Yampa, Desolation, Gray, Cataract, Black Rocks, and Westwater Canyons. The razorback sucker was once widely distributed, but today its populations are mostly older fish, concentrated in the mainstem reservoirs on the lower Colorado River, most notably Lake Mohave, and in the lower Yampa and Green Rivers of the Upper Basin. Five other native fishes might be included with these four in a community that inhabits the deeper and warmer habitats of the Colorado River system - the roundtail chub, the fan- 43