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, ftU1\l~ I C &hJe rSDf\ f rvlccrl1 ne':c , /q q.3 l I f.t~~mjllI~m~..j I i '-- THE SOUTHWESTERN NATURALIST 38(4):362-369 DECEMBER 1993 'lIb,> C{rgS Dece veys catel pers dow in I' stoc\ mgs Our squc to a-, the J pote squc EV ALVA TION OF AN INTRODUCTION OF COLORADO SQUAWFISH IN A MAIN STEM IMPOUNDMENT ON THE WHITE RIVER, COLORADO MELISSA A. TRAMMELL, ERIC P. BERGERSEN, AND PATRICK J. MARTINEZ Colorado Cooperative Fish 0- Wildlife Research Unit, 201 Wagar Building, Colorado State University, Fort Collins, CO 80523 (MAT, EPB) Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect, Fort Collins, CO 80526 (PfM) Present address of MAT: Utah Wildlife Resources, Moab Native Fishes Field Office, P.O. Box 388, Moab, UT 84532 temperature regimes (Tyus, 1991). The White River, previously free-flowing, was impounded by Taylor Draw Dam in 1985, 16 river-kilo- meters east of Rangely, Colorado, creating Ken- ney Reservoir. The dam effectively reduced the suitable habitat available to squaw fish in the White River by 80 km by preventing access to areas upstream from the dam. According to un- published findings of the Colorado Division of Wildlife, this represents about 16"lo of the doc- umented range in Colorado. There are no records of Colorado squaw fish reproducing in the White River and no suitable spawning conditions have been identified (Carl- son et aI., 1979; Haynes et aI., 1984). In light of this and because of construction mitigation agree- ments, Colorado Division of Wildlife (CDOW) and the United States Fish and Wildlife Service began a Colorado squaw fish stocking program in 1988, calling for 50,000 fingerling-age I Colorado squawfish to be stocked in each ofthe three years, 1988-1990. After the first stocking in 1988, sur- M comr Rese to th 1988 upstr becal strea the ( subd: Kl RK axis. its w the ( held Whi, deter reser an 0\ flow to all D, Cent Colo Fish the ~ 150,( was 96,5' ervoi alon! batd Kl --ting, was were Catc the t< effor ABSTRACT-We evaluated endangered Colorado squawfish (Ptychocheilus lucius) as a potential sportfish in Kenney Reservoir from 1988 to 1990 as part of a mitigation program for the construction of Taylor Draw Dam which impounded Kenney Reservoir on the White River, Colorado. A total of 96,597 fingerling squaw fish were stocked into Kenney Reservoir from 1988 to 1990. These fish quickly dispersed throughout the reservoir, and downstream into the White River. A small number moved upstream in 1990. A large proportion, associated with high discharge following stocking, exited over the spillway, and continued to move downstream. Catch-per-unit-effort declined drastically in both the river and the reservoir in 1989 and 1990. The rapid disappearance of squawfish throughout the study area was attributed to flow regime, movement patterns, mortality, sampling ineffectiveness or a combination of these. Telemetry observations of six adult Colorado squawfish revealed no difference in behavior attributable to wild or hatchery origin. Stocking squaw fish in Kenney Reservoir did not appear to be an effective mitigation procedure for habitat loss due to impoundment. The Colorado squaw fish PtychocheiLus Lucius is endemic to the Colorado River Basin. Once abun- dant, its decline has necessitated full protection as an endangered species (Federal Register, VoL 39[3]:1175, 1974). The historical range of this large cyprinid extended from Northern Sonora, Mexico to Green River, Wyoming, including much of the mainstem Colorado River and most of its larger tributaries (Colorado River Fishes Recovery Team, 1988). It is now restricted to a fraction of its former range, including the main stem Colorado River from Lake Powell to Pali- sade; the Green River below Brown's Park; the Yampa River below Craig; the White River be- low Rio Blanco Reservoir; and in portions of the San Juan River in Colorado, Utah and New Mexico (Colorado River Fishes Recovery Team, 1988; Tyus, 1991). Main stem impoundments on the Colorado River system have largely contributed to the de- cline of Colorado squawfish .populations by blocking migration routes and altering flow and waSt gill I wide