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Size Distribution Mean size of YOY Colorado squawfish was larger than 1995, but about average for the period covered by ISMP (Figures 4, 5; Tables A-3, A-4). Mean length was 39.6 mm (range, 20-81 mm) in Reach 1, 41.4 mm (19-75) in Reach 3, and 39.4 mm (25-60) in Reach 4. Calculations of mean total length in previous years used an arbitrary cutoff of 70 mm for the largest fish in the calculations. However, the length-frequency distributions (Figure 5) showed a smooth tail into the larger size classes with no obvious break point that might indicate capture of age-1 fish. Therefore all fish captured were included in the calculations- an addition of three fish in Reach 1 and sia fish in Reach 3. Sympatric Species The percentage of native fishes in the first seine haul in primary backwaters changed very little in reaches 1, 3, and 4. The largest change was in Reach 2 where native species declined from 12 0 of the total catch in 1995 to 4 % in 1996 (Figure 6; Table A-5). Catch rates for the three most common species (fathead minnow Pimephales promelas, red shiner G}-prinella lutrensis, and sand shiner Notropis stramineus) increased slightly in reaches 1 and 3 and decreased slightly in reaches 2 and 4. Catch per effort was not calculated for other species collected, but total number of all fish captured are listed in Table A-5. SUBADULT-ADULT COLORADO SQUAWFISH Sampling Reaches The subadult-adult Colorado squawfish monitoring program samples 186 miles of four rivers in the upper Colorado River Basin-the Green (five reaches: 1, RM 335-327; 2, 319- 300; 3, 260-245; 4, 115-96; 5, 56-40), Colorado (three reaches: 6, 154-132; 7, 99-86; 8, 68- 49), Yampa (three reaches; 9, 104-95; 10, 80-70; 11, 54-49), and White (two reaches; 12, 105-95; 13, 21-0) rivers (Figure 8). These reaches compose about 20 to 30% of occupied habitat within each of the four rivers. Also, two elective reaches were sampled in 1996: Green River-RM 215-230 (A) and Colorado River-RM 15-25 (B). The elective reaches are rotated among years and will be resampled on a four-year interval. 8