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A "Recovery Implementation Program for Rare and Endangered Fish Species in the Upper Colorado River Basin" (U.S. Fish and Wildlife Service 1986) has been prepared by a task group at the request of the Upper Colorado River Coordinating Committee to study the factors related to the low numbers of large river fishes and to take measures needed for the recovery of these fishes. POTENTIAL FOR COMPETITION/PREDATION BY INTRODUCED SPORT FISH The recovery implementation program identifies the possible need to control sport fish and other non-native species to minimize competition and predation on the rare fish. Furthermore, the FWS prepared a background opinion pertinent to Section 7 consultation on the operation of Taylor Draw Dam and Kenney Reservoir on May 22, 1982. This opinion states any species used to develop a sport fishery in the reservoir "should not compete with the endangered species in the White River". The following species accounts of the channel catfish, largemouth bass, bluegill, and black crappie (Pomoxis nigromaculatus) summarize the published literature on habitat and food habits and assesses the potential for competition with or predation upon the rare fishes. 4 Channel Catfish Habitat Channel catfish require warmwater habitat and inhabit both lentic and lotic environments (Carlander 1969). This,species is widely distributed throughout the mainstem Colorado River and its m?'or tributaries where it inhabits deep pools, eddies, shorelines and runs with silt/gravel/boulder substrates and backwaters with silt/sand substrates (Tyus et al. 1982). In the mainstem reservoirs, channel catfish are typically found in the littoral zone when the reservoirs stratify. Food Habits -Young channel catfish tend to feed primarily on aquatic insects or other bottom arthropods. This species is usually omnivorous but are known to become piscivorous when larger than 100 mm in total length (Carlander 1969). In food preference studies (Lewis, Anthony, and Helms 1965), channel catfish preferred crayfish of the right size over fathead minnows (Pime hales promelas), and these over bluegills, green sunfish (Lepomis cyanellus , and golden shiners (Notemi onus cr soleucas). In that study, some fingerling carp (Cypr inus carpio and bullheads ctalurus sp.) were eaten and tadpoles were killed but not eaten. Some evidence of competition by channel catfish with bluegills and redear sunfish (Lepomis microlophus) was observed by Brown (1965) who reported that reduced growth and condition probably occurred because of competition for chironomids. Reduced bluegill reproduction, in turn, was attributed to limited growth in largemouth bass.