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The degree of habitat overlap between Colorado squawfish and the other species examined in t iT study was estimated using the Schoener Index n ) and; n = number of habitat (Schoener 1970) where: 0 = 1-0.5 ?P - P A i=I xi categories, Px = the proportion of species x collected from habitat category i, and Py = the proportion of species y collected from habitat category i. For this analysis, 14 habitat categories were considered based on a breakdown of the' distribution of the five species along the derived discriminant function. In 1980, Colorado squawfish, red shiner, fathead minnow, (Pimephales promelas), and channel catfish (Ictalurus punctatus) from the Green River were preserved for stomach analysis. Individual food items were enumerated, weighed, and summarized as the mean of the weight percentages for each food item (Wallace 1981). is The degree of dietary overlap between Colorado squawfish and the other species was estimated using the Schoener Index (Schoener 1970: described above) where: n = number of food categories; proportion of food category i in the diet of species x; and Py = proportion food category i in the diet of species y. Wallace who applied indexes of dietary-overlap to fish, considered the Schoener Index to be the best available index when resource availability data are a sent. RESULTS Hahi t_at TTGa Age-0 Colorado s uaw were collected from a variety of habitats, but were most often found in e?hemera? backwaters, and depth, velocity and substrate 's measurements at these sites indicated their selection of areas with low water velocity, silt or sand substrate and moderate water depth (Fig. 1). These data undoubtedly are affected by varying sampling efficiencies in the different habitat d types and water depths and velocity; however, they accurately reflect the areas most commonly utilized by this species. The relative distribution of Age-0 Colorado squawfish over the range of physical variables measured in the study are consistent with those reported by Holden (1978). A total of 1124 small Colorado squawfish (30-60 mm TL) were collected and marked with unique fin-clips that indicated the habitat where they were originally collected. Almost 80% of these fish were initially collected in backwater habitat and 172 were subsequently recaptured. Most were recaptured in the habitat where they were initially collected; however, some individuals moved between backwaters and eddies or shoreline habitats. During periods of rapidly changing water levels, individuals (40-60 mm TL) were able to negotiate areas of relatively high water velocity to relocate in quiet water habitat. Catch-per-unit-effort (CPUE) of Colorado squawfish in backwaters fluctuated on a diel basis with highest catch rates occurring between about 1200 and 0200 hours. Catch rates in habitats outside backwaters were highest between 0400 and 1200 hours but did not exceed the CPUE in backwaters. These changes in CPUE were correlated (r = 0.6) with changes in water temperature throughout the da (Fig. 2). is 46