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<br />the UCRB (Tyus and Ndcirk 1990) and other similar western streams (Gerhardt and Hubert 1991) <br />have been found to be much lower than those in the midwestern and southwestern United States . <br />(Carlander 1969). However, sexual maturity appears to st>71 be reached around 300 mm in the <br />UCRB, which is similar to other regions (McMahon and Terrell 1982, Tyus and Ndcirk 1990, <br />Gerhardt and Hubert 1991). Differences in growth rates are ldcely due to suboptimal temperature <br />regimes. McMahon and Terrell (1982) reported that no growth occurs below 16° C and minimal <br />growth occurs at 21 ° C, with 26-29° C being the preferred temperatures. The temperature regime <br />in the Green River provides on average a 2-3 month growing season for channel catfish. ~ <br />In general, channel catfish prefer moving water with moderate to low velocity and substrate <br />dominated by cobble or rock (McMahon and Terrell 1982, Layher and Maughan 1985). Location <br />preference has been shown to depend on both the size of the fish and the season. Smaller fish in <br />the San Juan River tend to prefer lower velocities and substrates of sand to sdt (Lido and Propst ~ <br />1999). As channel catfish increase in size, they are found more fiequently in deeper and swifter <br />sections of a river (Jackson 1995, Gido and Propst 1999). <br />Channel catfish have been shown to negatively impact endangered fishes. Colorado pdceminnow <br />(~tychocheilus lucius) are known to prey on channel catfish, and several papers have documented ~ <br />catfish being lodged in the thmats of pdceminnow (McAda 1983, Pimental et aL 1985, Ryden and <br />Smith 2000). Large channel catfish also have a direct impact on native fish through predation <br />Bite marks were found on humpback chub by researchers that suggested they were from channel <br />catfish (ICaeding and Zimmerman 1983, Karp and Tyus 1990). If predation estino~ates are scaled <br />by density of predators throughout the Green River, channel catfish are of highest concern. i <br />Several nonnative fish removal options have been discussed within the Recovery Program: <br />mechanical removal techniques, recreation and commercial harvest, and use of chemicals (Lentsch <br />et al. 1996). Of the mechanical methods, baited fyke nets have been found to be the most efficient <br />gear type for capturing catfish (Pierce et aL 1981, Perry and Williams 1987, Gerhardt and Hubert <br />1991). However, in the San Juan River baited fyke nets were not as effective as electrofishing ~ <br />(Brooks et aL 2000). In addition, several researchers have shown that the effectiveness of <br />electrofishing varies as a tool for removing channel catfish (Holden and Stalnaker 1975, Tyus and <br />Ni7cirk 1990, Gerhardt and Hubert 1991, Ryden and Pfeifer 1999, Modde and Fuller 2002). <br />The goal of this project was to implement a fish control project that effectively reduced negative ~ <br />interactions between normative fish and native fish in the Green River, Utah. Specific objectives <br />were: <br />1) To reduce negative interactions of centrarchids and channel catfish with native species in the <br />Ouray reach (RM 248-228) of the Green River and determine if removal of these fish is ~ <br />effective and feasible. <br />2) To reduce negative interactions of channel catfish with native species in the Gray Canyon reach <br />(RM 142-132) of the Green River and determine if removal of these fish is effective and <br />feasible. <br />2 ~ <br />