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Colorado pikeminnow Number. The only listed fish found in the fish trap was the Colorado pikeminnow. Fifty-one sub-adult and adult Colorado pikeminnow passed through the passageway in these five years. This included 43 individual pikeminnow, six single repeat passages, and one double repeat passage. The number of pikeminnow collected in the trap by year was: 1996 (1); 1997 (18); 1998 (23), 1999 (5); and 2000 (4). Colorado pikeminnow used the passageway almost exclusively in August and July. Fifteen (29%) Colorado pikeminnow used the passageway in July, 35 (69%) in August, and onlyl (2%) in September (Figure 5). The earliest that a Colorado pikeminnow was collected in the fish trap was 2 July in 1998; the latest was 9 September in 1999 (Appendix; Table E.1.). The migration of pikeminnow through the passageway was during post-runoff which was associated with the period immediately following spawning (Appendix; Figure E.1.). Most (33) of the pikeminnow found in the fish trap were first-time captures; 17 of the 50 pikeminnow found in the fish trap had been captured previously (Appendix; Table E.1.). One pikeminnow accidently escaped over the concrete holding tank and upstream in the Gunnison River before it could be checked for a PIT tag, measured, and weighed. Seven different pi keminnow ascended the fish passageway twice; one of these pi keminnow ascended the passageway three different times. None of the these fish that reascended the passageway did so the same year (Appendix; Table E.1.). Interestingly, the one pikeminnow that ascended the passageway three times did so between the 3rd and 6th of August during 1997, 1998, and 1999. On two separate occasions in 1997 and six separate occasions in 1998, multiple captures of pikeminnow were recorded during the same day. On 3 August 1997, six fish were collected in the fish trap and on 4 August, four were collected. In 1998, three pikeminnow were collected in the fish trap each on 1 and 7 August and two fish were collected in the fish trap each on 15 July, and 6, 8, and 13 August (Appendix; Table E.1.). Three pikeminnow collected in the fish trap in 1997 were recaptures and had been previously captured in the Colorado River downstream from Moab, Utah (Appendix; Table E.1.). Size of Fish. The collective (n=50) mean TL for Colorado pikeminnow collected in the fish trap over these five years was 529 mm (Figure 6). The smallest pikeminnow was 383 mm; the largest, 763 mm. The mean TL of pikeminnow collected in the fish trap in 1996, 1997, 1998, 1999, and 2000 was 566, 534, 516, 544, and 555 mm, respectively (Appendix; Table E.1.). Sixty-percent of the pikeminnow that were caught in the fish trap were between 500 and 599 mm; 90% of the pikeminnow were between 383 and 599 mm (Figure 6). A study to estimate the size of sub-adult and adult Colorado pikeminnow from the lower (bottom of Westwater Canyon to the Green/Colorado River confluence) and upper (head of 22