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catch was high at all sites particularly when compared to the coincident roundtail catch. In July of <br />1996, catch of humpbacks was not especially high throughout the canyon, but more notable was <br />the poor catch of roundtails. The catch rate and recapture data do not suggest an influx of <br />humpbacks to Westwater Canyon, while the same data does not clearly indicate an exodus of <br />roundtials. Perhaps humpback chub were more active locally during this post runoff/post <br />spawning period making them more suseptible to our sampling techniques ? Conversely, the <br />roundtail may have been more sedentary. <br />The roundtail chub catch rates also fluctuated greatly from trip to trip with a project high of 1.26 <br />fish per hour recorded at the Cougar Bar in October, 1992 and the project low, 0.07, recorded at <br />the same site in Aprd of the same year (Figure 15). Project mesas by site were: RM 124.1 = .53; <br />RM 121.5 = .44; and RM 120.0 = .5288. A regression of CPEs against sampling date indicated <br />a strong negative trend in roundtail catch at all sites: RM 124.1 (R2 = -.64; x.045); RM 121.5 <br />(R2 = -.63; x.07); and RM 120.0 (R2 = -.74; x.013). <br />Early in the~study there was concern that there was a shift in Gila spp. composition toward <br />roundtails chubs, particularly in light ofpre-project sampling efforts (Figure 16). In this analysis <br />shifts in the Gila spp..dynamics become apparent. In the late 1980's humpback chub outnumbered <br />roundtails at all three sites often by a margin of 2:1 or more. The Mmer's Cabin (RM 124.1) <br />catch rates were much higher than the lower two sites with as many as 2.5 humpback collected <br />per hour in 1989, almost four times this project's highest CPE. <br />DAFT <br />33 <br />