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indicating suitable habitat is available for the smaller life stages of these native species given habitat conditions during the surveys. Mottled sculpin were present but not very common, so this fish is not a good indicator species for showing trends related to environmental perturbations, as is the case with the Yampa River. Sample size for fish less than 15-cm was highest in 2001 and this could reflect increased effort in sampling backwaters and shorelines or actual increases in number of small fish that year. Small fish typically increase in numbers during low flow conditions. Higher mean water temperatures are associated with low flow years and this means a longer growing season and more primary productivity. Given these conditions small-sized fish respond with more clutches and improved survival ofYOy' Flow conditions in both 2000 and 2001 may have been more conducive for small fish than in 1999. However, in order to document a biological response in the sunfish group, individual backwaters and shoreline data need to be examined and that was not main intention of this study. DOLORES RIVER The Dolores River site at Big Gypsum was sampled for the first time in 2000 and again in 2001. Species composition differed greatly between the two years for fish over 15 cm. In 2001 flannel mouth sucker (58%) was the most common fish over 15 cm sampled, but was only 16% in 2000 (Table 7). Roundtail chub were second most common at 25% in 2001 but was the most common species (55%) in 2000 (Table 7). Bluehead sucker was 6% of the sample in 2001 and only 2% in 2000. Together these native fish comprised 88% of the fish population in 2001, higher than the 73% observed in the 2000 sample. The most common non-native fish in 2001 was channel catfish at 8%, but was 16% in 2000 (Table 7). In the first less than 15 cm group, the number offish caught in 2001 (2,159) was much higher than in 2000 (577) (Table 7). Many more red shiners were observed in 2001 and this was the most common species at 36% in the less than 15-cm group. Speckled dace was the next most common fish under 15 cm at 18%. The large bodied natives, flannelmouth sucker, bluehead sucker and roundtail chub were also well represented in small fish group with 10%, 14% and 17%, respectively. Native fish comprised 58% of the <15 cm fish sample in 2001 compared to 87% in 2000 (Table 7). 26 I I I I I I I I I I I I I I I I I I I