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with the exception of a few large fish captured in fyke nets, were relatively low (Table 7). Conversely, relative weight was much higher for angler captured fish in 1999 than observed in 1998. However, this trend was not observed in fish captured by electrofishing in 1999, which had lower values similar than those observed by angling the previous year. Significant differences were observed in relative weight of angler caught fish among reaches during both years of the study (F=16.2, 3 df, P < 0.001 in 1998, and F=6.11, 3 df, P < 0.001 in 1999). Discussion Channel catfish were considered by most upper basin experts to be a threat to native fishes in the upper Colorado River basin (Hawkins and Nesler 1991) due both to direct biological impacts and wide distribution (Tyus and Saunders 1996). Lentsch et al. (1996) stated that channel catfish recruit readily and would be exceedingly difficult or impossible to control in the upper basin at this time. Although channel catfish reduction due to overharvest is well documented in larger alluvial rivers as a result of heavy commercial and or recreational fishing (Pitlo 1997, Gerhardt and Hubert 1991), removal efforts to control catfish in the alluvial reaches of the mainstem Green River with fyke nets failed to reduce numbers substantially, even though relatively large numbers of small fish were removed (Crowl and Badame 2000). Although Crowl and Badame (2000) captured large numbers of fish in passive gear, neither our study or Smith and Brooks (2000) successfully captured channel catfish with fyke or hoop nets in the Yampa and San Juan rivers, respectively. However, Smith and Brooks (2000) successfully reduced channel catfish numbers and size by electro fishing in the San Juan River. Electrofishing was successful in the San Juan River because 11