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enviromental adaptability of the species in order to allow enhance- ment of marginal areas and to adequately predict the impact of proposed development projects. The general types of summer habitat preferred by woundfin are known, but data is lacking on the micro- habitats--do preferred areas change with season, time of day, water temperature; how important is cover and what kinds of cover are utilized; how does habitat affect the competitive interactions with exotic species? A study is recommended to determine habitat require- ments, including year-round sampling of several stations and the gathering of physical-chemical parameters of the habitats sampled. Additional information should include water depth, velocity, temperature, substrate, cover, time/habitat and season/habitat relationships. These data will allow for the formulation of pre- ferred habitat profiles or electivity curves and assist agencies in predicting the impact of potential habitat manipulation on woundfin populations. This general methodology is being refined by the Instream Flow Group, U.S. Fish and Wildlife Service, Ft. Collins, Colorado. At the same time habitat-use information is being collected, a hydrologic study of the river should be undertaken that includes cross-sectional determinations of flow, depth, ana bottom type. These data can be used to map the river section and can also be correlated with the micro-habitat information to categorize pre-' ferred habitat, determine the amount available, and help establish minimum stream flows. A preliminary model of this type has been, developed by the Instream Flow Group which, when calibrated by several different flow regimes in a given area, can predict the amount of preferred habitat to be lost, given a~change or altera- tion in flow or channel morphology. In addition to this "short term" model, the hydrologic study should include studies to deter,- mine long-term impacts through an analysis of changes in sediment, transport capabilities. Such a study would assist in predicting the impacts of water projects on the Virgin River as well as other, similar rivers, and correlate with the electivity curves. The study to determine habitat requirements of the fish should be conducted for ht least a two .year period and will cost approx- imately $36,000. It will involve many separate mini-studies, such as food habitat studies, but needs to be done as a cohesive or single unit. The hydrologic study shou]_d last at least three years and should be funded at approximately $30,000/year for a total of $90,000. Both studies should be initiated at the same time and will probably result in better information if conducted by one research group. The initial research will center on the types of habitat found in the Virgin River, how that habitat is produced and maintained and when, where and why the woundfin used it. These data will lead to the formulation of a predictive model which will be field tested in the last year or two of the project. 18