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t found similar habitat relationships among these fishes in a diel study in the Green River in fall, 1980. Matthews and Hill (1980) found relatively little habitat partitioning among fishes in a shallow, sand-bottom stream compared to that of fishes in more structurally or physically diverse environments (see, for example, Werner et al. 1977). The dynamic nature of the discharge-influenced, predominately silt/sand-bottom habitats of the Green and Colorado rivers may thus contribute to the similarities in habitat use among the fishes that we examined. Moreover, the habitat parameters used in our analyses were quantified by relatively gross measurements when compared with those of other studies (e.g., Baker and Ross 1981). Only two depth, velocity and substrate measurements were made at the location of each seine haul, and some large areas (ca. 250 m2). The independent habitat vari analyses might not adequately describe variation among Position of the fish in the water column, for example, in the habitat partitioning of fishes in other studies seine hauls covered ables used in our the habitats sampled. an important component (Baker and Ross 1981), 1 might be important. However, high turbidity precludes the collection of such data in the Colorado River system. Results of our analyses suggest that water management directed toward increasing the amount of habitat available to age-0 Colorado squawfish, while reducing those of the most common introduced species that were examined, may not be feasible. There is simply too much similarity in habitat use among these species. Current studies of the habitat-use relationships of the Green River fishes are being conducted in greater detail than was possible in this study. Results of that study might aid our understanding of whether subtle ' but important differences in habitat use occur among species. Subtle 14