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<br />t <br /> <br />that form on downstream ends of backbar channels and terrace- or wall-based channels (Figure 2), <br />which remain connected to the main channel at baseflows. They may feed in these environments <br />(Valdez and Wick 1983) or simply move into low velocity habitats to avoid the higher flow of the <br />main channel (Doug Osmundson, U.S. Fish and Wildlife Service, Grand Junction, CO, personal <br /> <br />communication). Growth is optimum at 250C, based on experimental studies; Kaeding and <br />Osmundson (1988) showed that growth in the 15-mile reach of the Colorado River was reduced, <br /> <br />because maximum temperatures were less than optimum for maximum growth year around. <br />Warmer temperatures in backwater environments could offset the cold water effect (Wick et al. <br />1983), assuming food supply is adequate and small squawflsh can avoid predation. <br /> <br /> 600 1883 100 1884 <br /> z z <br />. I . I <br />.... ..... <br />.. E <br />" <br />~ : .. ~ <br /> ' . <br /> . ...~ ',oJ': ~ ~ <br />ft200 . <br /> \./\ i i <br /> . <br /> 100 , 100 <br /> '.::~ <br /> 20 25 30 II 202530 II 10 15 20 25 30 II 10 <br /> JIJN ..... AIL AUG <br /> 220 1885 <br /> '40 <br /> 100 <br /> ;;c <br />. I <br />"- 140 <br />.. <br />" <br />~ 100 !i: <br />It <br /> eo o , <br /> 20 <br /> 20 25 30 6 20 25 30 f. 10 If. 20 25 30 II '0 <br /> ~ ..... AIL AUG <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />Figure 3. Relationships of Colorado squawflsh spawning dates (vertical bars, data derived form <br />larval drift rates adjusted for hatching time) to Yampa River flows measured at the Deerlodge and <br />Maybell gauges in 4 different years. Number of fish represents number of larval fish sampled and <br />distributed according to estimated spawning date (from Nesler et al. 1988). <br /> <br />13 <br />