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<br />backwaters associated with the Green River are important nursery habitats for <br />larval and young-of-the-year (YOY) Colorado squawfish as well as other native <br />and nonnative fish species. <br /> <br />Radio telemetry studies of adult Colorado squawfish have revealed aggregations <br />of mature fish in the lower 20 miles of the Yampa River during early summer. <br />Evidence suggests both water temperature and hydrograph stage (Nesler et al. <br />1988; Tyus et al. 1987) and possibly other environmental factors, provide cues <br />for Colorado squawfish spawning. Spawning can occur from late June through <br />August. The squawfish eggs incubate in the substrate for about 6 days. After <br />hatching and emerging from the gravel, the larval Colorado squawfish drift <br />passively down the Yampa River to the Green River, then down the Green River <br />into low water velocity nursery areas such as backwaters. Backwater habitat <br />is important for young Colorado squawfish (Tyus et al 1987; Valdez and Wick <br />1983), provides some protection from fluctuating flows and high discharges, <br />and is generally more productive than main river habitats (Holland and Huston <br />1984). Kallemeyn and Novotny (1977), cited in Persons (1979), and Sheaffer <br />(1984) reported that many fish species preferred backwater areas, and that <br />backwater areas were important spawning and nursery areas for some species of <br />fish. The success (survival) of the larval and young Colorado squawfish in <br />Green River nursery areas probably depends on the ecological characteristics <br />of the habitat and their ability to exploit the available resources. Feeding <br />habits of young fish, food availability, some limnological characteristics, <br />and development and relationship of main river and backwater habitat in the <br />Green River occupied by young Colorado squawfish are not well known. <br />The goal of this study was to augment existing information on the physical, <br /> <br />9 <br />