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ABSTRACT <br />Recent investigations by Valdez and Masslich (1989} and Wick and Hawkins (1989} on <br />radiotagged adult Colorado squawfish and razorback suckers in the Green River and Yampa River <br />revealed a fidelity for overwintering sites in moderately deep, low-velocity habitats. Both species were <br />locally active, but rarely left a habitat, except during flow changes or to avoid ice jams and frazil ice <br />masses. Low, relatively stable winter flows are recommended to stabilize low velocity habitats, allow <br />formation of a persistent ice cover to insulate flows from supercooling, dampen moderate fluctuations, <br />and minimize incidence of ice jams and frazil ice. Further research is recommended to ascertain <br />needs of other life stages of Colorado squawfish, razorback suckers, humpback chub, and other native <br />species. Recommended studies include (1) a physical model of ice processes, (2) assessment of flow <br />regulation and ice on overwinter nursery habitat, (3) evaluation of physiological effects of supercooled <br />water on survival of age-0 Colorado squawfish, (4) assessment of Colorado squawfish nursery habitat, <br />(5) estimate of oveiwinter survival of age-0 Colorado squawfish, (6) survey of the Lake Powell inflow <br />for Colorado squawfish, (7) evaluation of winter and spring flows on movement, dispersal and survival <br />of young Colorado squawfish, and (8) assessment of predation on age-0 Colorado squawfish in <br />supercooled winter conditions. <br />vii <br />