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Habitat Preferences of all Fish Species This section presents data obtained from the enumeration of fishes collected in habitat types (Figure 7). Habitat preference is inferred from conditions measured at point of capture. Caution should be used when interpreting the information presented on number of fishes col- lected in a given habitat type using all gear types in all strata. These habitat types are not uniformly represented in all strata. How- ever, all habitat types within a station were sampled using at least one gear type. More complete analysis of these data will be made later using a number of variables including stratum, habitat type, water depth, water velocity and substrate type. Backwaters generally contained more fish than any other habitat, primarily the small species of minnows (e.g., red shiner and fathead minnow), young and juveniles of the larger species (e.g., Colorado squawfish, flannelmouth sucker and Gila). Adults of species other than the small, cyprinids were uncommon. Eddies frequently contained the greatest number of adults of the larger species and occasionally contained large numbers of young red shiners, carp, roundtail chub and channel catfish. Collections made in shoreline habitat also contained high numbers of the larger species as well as red shiners. Adult bluehead suckers, flannelmouth suckers, Colorado squawfish and Gila spp. were collected from this habitat type in some or all strata. No razorback suckers were collected in this study, nor have they been recorded from the White River in recent times (Lanigan and Berry 1981). Fishes of the genus Gila were collected in all strata during standardized sampling. Stratum V contained the largest number of Gila spp. One suspected humpback chub was collected from stratum Z at the Mountain Fuel Bridge; however, this specimen was not preserved and its identification has not been confirmed. Analysis of measurements taken from other Gila spp. indicated all other Gila spp. collected were round- tail chubs.- The numbers of fish species found in a stratum generally reflects the diversity of habitats or the environmental conditions in that stratum. Strata X and V contained the largest numbers of fish species with 12 and 13, respectively (Figure 8) (genus Gila included as one species). Stratum W contained the lowest number of species with nine, and strata Y and Z each contained 10 species. Fish species diversity was obtained for each strata by calculating the Shannon-Weaver diversity index (Green 1979). (This index was highest for strata X, V and W) 0.75, 0.64 and 0.63) and lowest for strata Y and Z) (0.56 and 0.45). These indices appear to be directly proportional to stream gradient. 24.