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Humpback chub Rapidly declining summer flows could adversely affect spawning and nursery habitats in canyon-bound reaches by concentrating fishes in suboptimal habitats and increasing the potential for disease, competition, predation and hybridization. The aquatic food base in the upper Green River may no longer be adequate to support high chub populations. Gradually declining flows following peak spring runoff is desired. Higher water temperatures in summer may aid growth of channel catfish, a potential competitor and predator of humpback chub. Razorback sucker Recruitment failure of razorback sucker presumably occurs in late spring and early summer. This failure has been linked elsewhere with predation by introduced fishes (including common carp and channel catfish), but may also be associated with loss of warm, flooded bottomlands, reduced river temperatures, and erratic flows. Lower spring flows may favor growth and proliferation of potential predators. Autumn and Winter (September 23-March 20) Colorado squawfish Colorado squawfish remain active in autumn and winter and utilize a variety of low-velocity habitats. High autumn and winter flows may reduce availability of preferred habitats and result in poor fish condition. Unusually high flows in autumn reduce availability of nursery habitat for young Colorado squawfish. Stable winter flows reduce ice scouring of shoreline habitats used by adults and young and may reduce stress to the fish associated with induced movements. Flows maximizing backwater habitats (quality and quantity) used by juveniles and adults should be determined and provided, at least during early autumn and late winter. Humpback chub Habitat use and flow needs of the humpback chub in the lower Yampa River during low-flow events noted that Gila species inhabit pools and semi-isolated eddies. Such low-flow conditions in the autumn and winter do not occur in the Green River. On the contrary, flows at this time of year are higher than historic, and these higher flows may degrade winter chub habitat while improving it for introduced fishes, particularly carp and channel catfish. Lower winter flows in the Green River are judged as more acceptable than present conditions. Razorback sucker Fluctuating winter flows with icy conditions may induce greater movement of overwintering adults with added stress. High winter flows also flood low- velocity habitats used by the fish. The early spring spawning of razorback sucker indicates that winter habitat conditions can affect gonadal maturation 30