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During the five years that the fish trap was operated between 1996 and <br />2000, 43,123 fish consisting of 19 different fish species (6 native and 13 <br />nonnative) and three catostomid hybrids were collected and counted. Large-bodied <br />native fishes consistently comprised about 93% of this total for each of these <br />5 years. Fish captures were highest in 1997 (12,233) for both native (11,547) <br />and nonnative fishes (686), followed by 1996 (8,375), 1999 (8,264), 1998 (7,589), <br />and 2000 (6,662). Generally, fish trap captures steadily increased in April, <br />May, and June. Captures peaked in July and rapidly declined in August, <br />September, and October. Total fish trap captures varied among months and among <br />the five years of operation. For the five years, the highest fish use occurred <br />in July and June (10,503 and 8,971, respectively,) followed by May (8,228), April <br />(5,593), August (5,002), September (2,213), March (1,949), and October (664). <br />Native fish used the passageway more often in June and July which <br />corresponded with the runoff and subsequent post-runoff period in the Gunnison <br />River. Native fish use tended to be highest in June in 1997, 1998, and 1999, <br />although the overall 5-year total number (9,320) indicated that July was the <br />highest month of use. Nonnative fish consistently used the passageway the most <br />in July (1,083), followed by June (348), and August (425) between 1996 and 1999. <br />Only in 2000 did nonnative fish use the passageway more in June rather than July. <br />The most numerous native fish collected in the fish trap was the bl uehead sucker. <br />The native flannelmouth sucker was the second most abundant fish collected. <br />White sucker was the most numerous nonnative fish in the fish trap, followed by <br />channel catfish, common carp, and black bullhead. Use of the passageway by <br />channel catfish coincided mostly with that of Colorado pikeminnow. <br />Surge or pulse migrations when large numbers of fish moved at one time, <br />through the passageway were documented. Most of these fish were bluehead sucker <br />and flannelmouth sucker. On most days preceding and following these events, no <br />or few fish would be found in the fish trap or passageway. The highest single <br />daily count was 1,179 in mid-April 1998 which included flannelmouth and bluehead <br />sucker and roundtail chub. <br />Evidence of "fallback", fishes that had passed upstream through the <br />passageway and subsequently fell back over the dam and ascended again, was <br />provided in 1996 by marking individuals of three non-listed, native species and <br />three of the most common nonnative species. Flannelmouth sucker, bluehead <br />sucker, and roundtail chub, along with three nonnative fishes that were captured <br />in the fish trap were used. About 2%, 9%, and 5% of the three marked native <br />fishes, three nonnative fishes, and two hybrid suckers, respectively, reascended <br />the passageway. Thirteen (25X) of the 51 Colorado pikeminnow that passed through <br />the passageway fell back over the Redlands Dam. Five of eight radio-tagged <br />pikeminnow that were released upstream of Redlands Dam subsequently fell back <br />over the dam. <br />Recapture of three native fish species, flannelmouth sucker, bluehead <br />sucker, and roundtail chub, that had previously been collected in the fish trap <br />and marked, revealed that they had dispersed upstream from the Redlands Dam <br />passageway. Some were recaptured as far upstream as 57 miles, near the base of <br />Hartland Diversion Dam. <br />xiii