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General Tracking: Habitat Utilization For bonytail tracked in the Colorado and Green rivers during 1997 through 2000, specific habitat locations were recorded for 574 contacts. Contacts were most frequent during the fIrst two months following release. Due to minimal longitudinal movements in this period, habitat utilization was likely dependant on habitat available near the release sites. In the Colorado River, runs and shorelines were the primary habitats used during March through May. Habitat use varied widely during June while fish were making longer longitudinal movements (Figure 17). By July and August bonytail in the Colorado were found primarily in eddies and runs (Figure 17). The initial pattern observed in the Green River was different, with the fish remaining in the eddy in which they were released. After flows peaked on the Green River, however, the pattern of habitat use was similar to that observed in the Colorado River. As was observed by Chart and Cranney (1993) bonytaillocated in eddies were often reported to be near or in the eddy line. During the cool water months of October through December, bonytails were found in runs on 68-83% of the contacts (Figure 17). Although many habitats were utilized throughout the study period, we believe that after the period of acclimation adult bonytail were selecting areas which offered a combination of eddy and run habitats. This is very similar to the assertions by Chart and Cranney (1993) that eddy line habitats were preferred by healthy adult bonytail. In addition, the few collections of wild bonytail in the Colorado and Green rivers have also suggested a preference for eddies or areas adjacent to deep swift water (Vanicek 1967; Kaeding et al. 1986; Valdez 1990). Intensive Tracking:: Summary The typical pattern observed for radio-tagged bonytail was a relatively sedentary acclimation period of one to two months following release. During this period, bonytail were typically in deep portions of eddies or runs 15 to 30 meters (m) from shore during the diurnal period, with occasional movements into shallower habitats around dawn. As water temperatures and flows increased, individuals began increasing both local and longitudinal activity. During late-May through August, diurnal positions were still primarily in deep portions of eddies or runs 15 to 30 m from shore. However, crepuscular activity increased with fish moving into shallow areas generally less than 5 m from shore. These results are nearly identical to those compiled by Chart and Cranney (1993), which can be referred to for a comprehensive analysis of adult bonytail diel activity patterns. In future monitoring of the adult portion of the bonytail population, effectiveness may be increased by focusing on either late-spring or early-fall crepuscular electrofIshing or trammel netting in appropriate habitats. 17