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.... 16 Backwater nursery habitats were influenced by inundation and resuspensian of .organic material from shorelines during increased flaws and ultimately influenced backwater nursery habitats. This energy source was important for standing crops of fish food organisms (Grabowski and Hiebert 1989). Backwaters in the Ouray area, where young Colarado squawfish were most abundant, were richer in faod, than upstream areas studied. Reduced water- level fluctuations in that area resulted in more stable backwater habitats and possibly reduced the export of nutrients and food (Grabowski and Hiebert 1989). Juven il es Colorado squawfish reach about 74 mm total length by age-2j their greatest growth occurs during their third and fourth years just prior to attaining maturity. Little is known about the habitat requirements of juveniles, but they were captured in a variety .of shoreline habitats including backwaters and flooded bottomlands. Juvenile Colarado squawfish may be more numerous in the lawer Green River (Tyus et al. 1987) because of the downstream drift .of larvae. If so, a long-distance upstream mavement by juveniles is needed ta repopulate upstream areas. Because only large-sized fish are found in the upper Vampa River and the highest concentratian of juveniles .occur in the lower Green River, upstream mavements probably occur during the late juvenile .or early adult stages (Tyus 1986 and 1990; Tyus et a1. 1987). These movements require unrestricted access, which is considered essential ta the species. HUMPBACK CHUB General Status Humpback chub originally inhabited the main stem Colorado River fram what is now Lake Mead to the canyon areas of the Green and Vampa River basins. They were considered less common than other endemic fish of the region but occur in fairly large numbers where reproducing populations exist. The greatest concentrations of humpback chub .occur in the Grand Canyan portion of the Colorado and Little Calorado Rivers and WestwaterjBlackrocks region of the Colorado River. Smaller populations and incidental catches are reported from Vampa River; Desalation, Gray, and Whirlpool Canyons of the Green River; and Cataract Canyon of the Colorado River. The recovery goals for humpback chub established through the Recovery Program are to "maintain or establish and protect five self-sustaining populations, natural habitat, and two refugia." Adults Humpback chub occur in several canyon-bound sections of the Green River basin, including the lower portion .of the Little Snake and Vampa Rivers and Whirlpool, Desolation, and Gray Canyons of the Green River (Holden 1978; Tyus et al. 1982a, 1982b, and 1987; Karp and Tyus 1990a; M. Moretti and E. Wick, pers. comm.). Surveys canducted prior to and after closure of flaming Gorge Dam indicated that all three farms of Colorado River chubs were locally common in the Green River. This includes bony tail and roundtail chubs in upper Green River above Ouray, Utah. Humpback chubs occurred in Desolation and Gray Canyons and in the Flaming Gorge basin of the upper Green River (Smith 1960;