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relationship between environmental conditions (backwater temperatures, <br />depths, and sizes, and substrate and turbidity) with the presence/absence <br />of Colorado squawfish. Fish were considered present if seining caught at <br />least one fish; they were considered absent if none were caught. <br />Results <br />Larval distribution and hatching. A total of 11,379 age-0 Colorado <br />squawfish were captured in the lower Yampa and Green River study area: 601 <br />were caught in drift nets in June and July, 3,079 in seines in July and <br />August; 6,459 in seines in September and October; and 1,240 in seines in <br />April. <br />No Colorado squawfish larvae were found in the Green River above its <br />confluence with the Yampa River (RK 552-584), or in the lower 225 km of <br />the White River. Larvae were present from RK 29 on the Yampa River <br />downstream to RK 35 on the Green River, the lowermost RK of our study <br />area. July-August seining showed two areas of larval abundance: one <br />downstream of the Yampa River, but upstream of Gray Canyon (i.e., near RK <br />480), the other downstream of the Gray Canyon spawning area (i.e., near <br />RK 112; Figure 2). <br />A total of 6,459 postlarvae captured from late-September to October <br />showed spatial distributions below the spawning areas that were similar to <br />the July-August distribution. One distribution occurred between RK 335- <br />450, or about 150 km downstream of Yampa Canyon spawning area and another <br />was about 130 km downstream of Gray Canyon (between RK 50-160, Figure 3). <br />Accordingly, higher catches occurred in the low gradient reaches of strata <br />A (22.4/100m2 seined), B (10.4/100m2), E (6.3/100m2) and F (10.5/100m2). <br />8 <br />