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9. From the data collected, we were unable to determine the 'threshold' or minimum flow when Colorado pikeminnow vacated the plunge pool and 2.3-mile reach of the Lower Gunnison River (Objective number 5). RECOMMENDATIONS The following recommendations and rationale for these recommendations are provided for the continued operation of the passageway at Redlands Dam. 1. Operate the passageway from 1 April through 15 September. Rationale: If the intent is to operate the ladder to pass non-listed native fishes in addition to listed fishes, then the passageway should be opened as early as the first of April. Eighty-seven percent of the native fishes that used the passageway over the five years, did so between 1 April and 31 August. Thirteen percent (5,431 fish) of all native fish used the passageway during April from 1997 to 2000. Only 3.9% (1,571) of all fish that used the passageway did so after 15 September during all five years combined. July and August were the primary months that the Colorado pikeminnow used the passageway. Only one pikeminnow used the passageway in early-September. Operation of the fish trap should include checking the fish trap at least every other day during weekdays, and on weekends, if manpower is available. Fish should be sorted by species and enumerated. The number of Colorado pikeminnow collected in the fish trap declined in 1999 (5) and 2000 (4) from the high of 1998 (23) and 1997 (18), and the number of flannelmouth sucker, bluehead sucker, and roundtail chub declined steadily over the first five years of operation. If this trend is a concern, the number of listed and non-listed native fishes that are found in the fish trap should be compared with past use. Currently, it is uncertain if adult razorback sucker will become established in either the Upper Colorado or Gunnison rivers. If razorback sucker become established in these rivers, it is unknown if or at what times of the year they would move through the passageway. The passageway should be operated at least during the spring period when adult razorback sucker migration is associated with spawning (May and June). 49