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with a percentage of38%. Below the study area the percentage of blue head sucker was 15% and above it was 25%, and the mean of all three was 26%. The study area had the lowest percent of round tail chub (3%). The percentages of round tail chub below and above the study area were 6 and 7%, respectively. Channel catfish were the only non-native predators in the main channel. Its' composition was 5% in the study area, 6% below and 13% above. Native fish comprised 82% of the total in the study area, 75% below and 63% above and 72% for the mean of the three sites. Colorado pikeminnow were only 0.2% ofthe catch (Table 3). Table 3: Species composition for fish >15 cm at the IS-MILE Reach, Colorado River station in October 1999. Column 2, has both percent composition for >15 cm and for (total fish) sampled in five backwaters. 1. STUDY 2. STUDY 3. BELOW 4. ABOVE 5. Combined AREA AREA STUDY STUDY Weighted Main Channel Backwater AREA AREA Mean Species 4.0 Ian n-5 4.5 Ian 4.8 1,3 &4 Flannelmouth Sucker 40.6% 21.7% (9.6%) 54.9% 31.5% 42.7% Bluehead Sucker 38.1% 0.3%(1.1%) 14.7% 24.6% 26.1% Roundtail Chub 3.1% 4.0% (168%) 5.6% 6.6% 5.0% Colo. Pikeminnow 0.1% 0 0.2% 0.5% 0.2% White sucker 2.2% 16.5% (8.9%) 1.6% 3.5% 2.4% White X Flannelmouth 0.7% (0.3%) 0.8% 0.5% 0.7% White X Bluehead 1.3% 0 1.4% 1.1% 1.3% Channel Catfish 4.6% 0 6.1% 13.0% 7.7% Carp 8.5% 39.4% (14.6%) 13.5% 17.6% 12.9% Smallmouth Bass 0.0% 0.4% 0.2% Largemouth bass 0.1% 5.9% (5.9%) 0.1% 0.2% 0.1% Green Sunfish - 0.9% (5.3%) 0.0% 0.2% 0.0% Brown trout 0.4% (0.1%) 0.5% 0.5% 0.5% Rainbow trout 0.03% 0.2% 0.1% Black Bullhead 03% 11.2%(41%) 0.1% 0.3% 0.2% NNC' - (32.5%)' Razorback Sucker - (0.7%) Bluegill - (01%) Sample size 3144 (3209) 322 (1071) 946 (961) 654(705) Recaptures *NNC is non-native cyprinids, the red shiner, sand shiner and fathead minnow. Since we did not attempt to make a total capture ofNNC, their percentage in backwaters is higher. 32 I I I I I I I I I I I I I 1 I 1 I