7195 - Laserfiche WebLink

Home Browse Search

7s NESLER ET AL. ture, signals the approach of baseline flow condi- tions and the emergence of favorable backwater habitat downstream. Colorado Squawfish Spawning and Water Development Flow and temperature are known key elements in the spawning requirements of Colorado squawfish. Our hypothesis is based on indirect evidence linking estimated spawning activity and flows, but verification of this and other require- ments of the spawning populations of Colorado squawfish may not be possible until the species' status improves. Considerable effort has been expended to establish flow requirements for vari- ous life history stages of the Colorado squawfish. Depth and velocity curves describing habitat suit- ability are being constructed for five life stages of the Colorado squawfish including spawning. These recommendations will guide continuing re- covery programs and consultation requirements for water development projects. An important consideration that must be acknowledged in these recommendations is .that the native fish fauna has adapted to an environment of cyclical patterns. However variable the absolutes, such as maxi- mum spring flow, the pattern of change and sea- sonal flux tends to occur regularly and predict- ably. It is logical to assume that species adapted to such an environment also become more or less dependent upon these cycles and fluxes. Hubbs (1972) suggested that asteady-state environment is deleterious to most species of native stream faunas and floras. Few streams can be character- ized as stenotypic environments, so any manipu- lation of a stream that dampens environmental flux may be considered less favorable for the native biota. Colorado squawfish have been ob- served to migrate and spawn in a considerable range of flows since 1980. Holden (1980) and Haynes et al. (1985) concluded, from evidence of relative yearly spawning success and year-class abundance that high spring flows were necessary to create and maintain suitable spawning habitat. Tyus (1986) hypothesized that the Colorado squawfish, as a large, long-lived riverine species, relies on the production of many progeny during wet years. Our results suggest that flow fluctuations during late June to early August may have important influences upon successful spawning by Colorado squawfish. These results may also have a direct bearing upon recommended operations criteria for water projects in order to protect this species in regulated river environments. It may be necessary to simulate natural flow patterns containing spring runoff peaks and baseline flow spikes to stimulate successful spawning by the Colorado squawfish in downstream spawning areas. Acknowledgments The data base used here was collected during several studies conducted by the Colorado Divi- sion of Wildlife. These studies have been funded through Colorado's Nongame Wildlife Income Tax checkoff program and through Section-6 funding from the U.S. Fish and Wildlife Service under the authority of the Endangered Species Act of 1973. We acknowledge the helpful ideas contributed by colleagues within the interagency coalition of the Colorado River Fishes Project in the Upper Basin, members of the Desert Fishes Council, and participants in the 11th Larval Fish Conference. References Beamesderfer, R. C., and J. L. Congleton. 1981. Spawning behavior, habitat selection, and early life history of northern squawfish with inferences to Colorado squawfish. University of Idaho, Idaho Cooperative Fishery Research Unit, Report 2, Moscow. Bye, V. J. 1984. The role of environmental factors in the timing of reproductive cycles. Pages 187-205 in G. W. Potts and R. J. Wootton, editors. Fish repro- duction: strategies and tactics. Academic, London. Carlson, C. A., and R. T. Muth. In press. The Colorado River: lifeline of [he American Southwest. Cana- dian Journal of Fisheries and Aquatic Sciences. DeVlaming, V. L. 1972. Environmental control of tel- eost reproductive cycles: a brief review. Journal of Fish Biology 4:131-140. Hamman, R. L. 1981. Spawning and culture of Colo- rado squawfish in raceways. Progressive Fish-Cul- turist 43:173-177. Harden-Jones, R. F. 1981. Fish migration: strategy and tactics. Society for Experimental Biology Seminar Series 13:139-165. Haynes, C. M., T. A. Lytle, E. J. Wick, and R. T. Muth. 1984. Larval Colorado squawfish (Ptycho- cheilus Lucius Girard) in the upper Colorado River basin, Colorado, 1979-1981. Southwestern Natural- ist 29:21-34. Haynes, C. M., R. T. Muth, and T. P. Nesler. 1985. Identification of habitat requirements and limiting factors for Colorado squawfish and humpback chub. Colorado Division of Wildlife, Job Final Report 5E-3-4, Fort Collins. Holden, P. B. 1980. The relationship between flows in the Yampa River and success of rare fish popula- tions in the Green River system. BioWest, Inc., PR-31-1, Logan, Utah.