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<br />HumDback chub <br /> <br />Rapidly declining summer flows could adversely affect spawning and nursery <br />habitats in canyon-bound reaches by concentrating fishes in suboptima1 <br />habitats and increasing the potential for disease, competition, predation and <br />hybridization, The aquatic food base in the upper Green River may no longer be <br />adequate to support high chub populations. Gradually declining flows following <br />peak spring runoff is desired, Higher water temperatures in summer may aid <br />growth of channel catfish, a potential competitor and predator of humpback <br />chub. <br /> <br />Razorback sucker <br /> <br />Recruitment failure of razorback sucker presumably occurs in late spring and <br />early summer. This failure has been linked elsewhere with predation by <br />introduced fishes (including common carp and,channel catfish), but may also be <br />associated with loss of warm, flooded bottomlands, reduced river <br />temperatures, and erratic flows. Lower spring flows may favor growth and <br />proliferation of potential predators. <br /> <br />Autumn and Winter (September 23-March 20) <br /> <br />Colorado sauawfish <br /> <br />Colorado squawfish remain active in autumn and winter and utilize a variety of <br />low-velocity habitats, High autumn and winter flows may reduce availability <br />of preferred habitats and result in poor fish condition. Unusually high flows <br />in autumn reduce availability of nursery habitat for young Colorado squawfish. <br />Stable winter flows reduce ice scouring of shoreline habitats used by adults <br />and young and may reduce stress to the fish associated with induced movements. <br />Flows maximizing backwater habitats (quality and quantity) used by juveniles <br />and adults should be determined and provided, at least during early autumn and <br />late winter. <br /> <br />HumDback chub <br /> <br />Habitat use and flow needs of the humpback chub in the lower Yampa River <br />during low-flow events noted that Gila species inhabit pools and semi-isolated <br />eddies. Such low-flow conditions in the autumn and winter do not occur in the <br />Green River. On the contrary, flows at this time of year are higher than <br />historic, and these higher flows may degrade winter chub habitat while <br />improving it for introduced fishes, particularly carp and channel catfish. <br />Lower winter flows in the Green River are judged as more acceptable than <br />present conditions. <br /> <br />Razorback sucker <br /> <br />Fluctuating winter flows with icy conditions may induce greater movement of <br />overwintering adults with added stress. High winter flows also flood low- <br />velocity habitats used by the fish. The early spring spawning of razorback <br />sucker indicates that winter habitat conditions can affect gonadal maturation <br /> <br />30 <br />