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In 2004, mean CPUE offlannelmouth sucker was about one third that of2003 but still represents an increasing trend since 2000 (Figure 9). Catch rates of flannelmouth suckers collected in the Little Colorado River and in the mainstem Colorado River within Grand Canyon between 1991 and 2000 suggest that the population offlannelmouth suckers was stable and showed few strong year classes (Figure 2). The population offlannelmouth suckers sampled during this time was dominated by age 0 fish (<150mm) and adults (>400mm). Recent monitoring in the Little Colorado River (2002-2004) as well as electrofishing in the mainstem shows evidence of increased abundance of sub-adult flannelmouth suckers. This trend was most evident in mainstem electrofishing data between 233 km and 346 km downstream of Glen Canyon Dam (Scott Rogers AGFD, personal communication). The observed trend corresponds temporally and spatially to an increased number of days with water temperature greater than 150C (Figure 12). It is likely that increased river temperatures resulting from lower Lake Powell water levels and stable summer discharges from Glen Canyon Dam are partially responsible for the increased recruitment offlannelmouth suckers within the Little Colorado River. One flannelmouth sucker initially tagged at rkm 193 below Shinumo Creek in the Mainstem Colorado River was subsequently caught in 2004 in the LCR (Appendix). Adult flannelmouth suckers are known to make long distance upstream movements when they reach reproductive size. Catch of blue head suckers ::::150 mm TL continued to increase in 2004(Figure 10). Large numbers of age 2 and 3 flannelmouth suckers continue to be caught compared with previous years (Figure 2). High recruitment of flannelmouth and bluehead suckers may have been caused by the low summer steady flows in 2000 which increased mainstem water temperature by approximately 2 oC in the lower river. Subsequent warmer mainstem water temperatures caused by drought conditions and lowered water levels in Lake Powell (Susan Hueftle, USGS unpublished data) may have also led to increased survival of suckers. The removal of rainbow trout in the area around the confluence of the Little Colorado River may also be partly responsible for the increased catch of suckers within the Little Colorado River. One bluehead sucker was recaptured in 2004 but the tag information is not currently in the GCMRC 14.5 database. (See Appendix). The low number of recaptures recorded for blueheadsucker suggests tagging mortality may be high and indicates further research is needed on tag retention and tag related mortality in bluehead suckers. 10