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provision of a proper flow regime to optimize backwater habitats, i.e., <br />summer flows more like historic conditions. <br />Growth and survival.-We expected greater growth and better overwinter <br />survival of age-0 fish in the lower Green River because of warmer water. <br />However, we found that age-0 fish in the upper nursery area were the same <br />average annual size, and even larger than the lower area. We assume that <br />other environmental factors, (e.g., habitat availability and food <br />abundance) are more important for growth in some years, at least. <br />Reduced relative abundance and growth of age-0 fish in 1983 and 1984 <br />was attributed to abnormally high summer flows from Flaming Gorge Dam. <br />These flows inundated nursery habitats and reduced water temperatures in <br />the upper Green River. Low summer flows, however, were associated with <br />greater catches of age-0 fish and growth. Although it was impractical to <br />count all backwaters by boat because of the width of the river and limited <br />manpower, we observed fewer backwaters during high flow years (1982,1983 <br />and 1984) and more during low and average flow years (1979-1981, 1987- <br />1988). These observations were similar to results of a Bureau of <br />Reclamation study conducted 1986-1988 on four reaches of the Green River. <br />Using aerial photographic mapping of shoreline habitats at different water <br />levels, they found that backwaters were reduced in area when flows in the <br />Green River increased above average historic summer flows (M. Pucherelli, <br />U.S. Bureau of Reclamation, personal communication). Thus, high flows not <br />only reduced catches, but also reduced the total amount of backwater <br />habitat available. We were concerned that higher flows might have reduced <br />our success in catching young fish in 1983 and 1984, and biased our <br />results. However, spring sampling in 1984 produced only one age-1 <br />16 <br />