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<br />in backwaters of the upper nursery area when area exceeded 750 m2 <br />(G-test, P < 0.01). However, larger backwaters were more diverse, and <br />backwater size was correlated with the number of species (r = 0.887, <br />P < 0.01). <br /> <br />DISCUSSION <br />We scheduled drift samples to coincide with the reproductive period <br />of Colorado squawfish (July and August), and this was presumably <br />reflected in the high numbers of larval Colorado squawfish captured. <br />Although drift samples were restricted to near-shore habitats, Colorado <br />squawfish was the most abundant fish, followed by suckers and speckled <br />dace. Channel catfish was the only non-native fish whose numbers <br />exceeded 1% of the total in the near-shore drift, and others have noted <br />that this species was even more abundant in deeper drift samples (Nesler, <br />1987). This suggests that of the introduced fishes, channel catfish is <br />the only species whose reproductive strategies are somewhat similar to <br />larval Colorado squawfish. <br />Young Colorado squawfish occupied backwaters with a wide range of <br />environmental conditions, but was prevalent in those with water depths <br />greater than 15 cm. We detected no temperature preferences for backwaters <br />in the lower Green River, but the fish were more abundant in warmer <br />backwaters in the upper Green River, avoiding temperatures less than <br />10oC. The difference in average backwater temperatures between the upper <br />and lower Green River (5.60C) was almost identical to differences in <br />average temperatures (5.70C) used by the fish in the two locations. <br />Laboratory findings suggest that yearling Colorado squawfish prefer <br /> <br />10 <br />