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Tae~E 2. -Total numbers of Colorado pikeminnow captured during ISMP sampling, 1986-2000. Original Reaehes ,Alternating Reaches Sub Sub Year Green Colorado White Yampa Total Green Colorado White Total Total 1986 42 11 5 17 75 0 0 0 0 75 1987 47 12 3 5 67 0 0 0 0 67 1988 34 4 5 6 49 0 0 0 0 49 1989 52 5 19 5 81 0 0 0 0 81 1990 77 4 22 5 108 0 0 0 0 108 1991 73 16 14 13 116 0 0 0 0 116 1992 85 31 19 18 153 0 0 0 0 153 1993 82 24 22 15 143 0 0 0 0 143 1994 99 33 31 14 177 54 0 0 54 231 1995 139 41 34 14 228 41 0 0 41 269 1996 ll9 40 39 14 212 9 it 0 20 232 1997 114 32 59 18 223 0 0 0 0 223 1998 143 31 38 19 231 60 0 0 60 291 1999 118 20 51 21 210 0 3 13 16 226 2000 195 12 91 16 314 112 3 0 115 429 a Numbers include some fish handled more than once in the same year. Numbers are broken down by sampling reach in Appendix Tables A-1-A-4. Colorado pikeminnow Relative Abundance Mean CPE was significantly different in at least two years in all rivers except for the Yampa River (ANOVA, Ps0.05; Table A-9). Pairwise comparisons using the Tukey-Kramer test (considered a conservative test) did not detect significant differences among individual years in either the Colorado or Yampa rivers (Table A-10). However, comparisons using Fisher's LSD test (a more liberal test) showed significant differences in all rivers (Table A- 10). In general, CPE in later years was significantly greater than CPE in early years of ISMP. More significant differences among years occurred in the Green and White rivers than in the Colorado and Yampa rivers (Table A-10). Mean CPE was significantly related to time in all rivers and slopes of the regression lines were always significantly different than 0 (Table A- 9). Overall, change in CPE indicated increasing Colorado pikeminnow abundance in the four major rivers of the upper basin throughout the 15-year study, especially the Green and White rivers. 7