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Razorback Suckers Net long-range movement by radiotagged adult razorback suckers in the Green River averaged 3.4 km (n=8, range of 0.0-16.9 km) and 4.7 km (n=9, range of 0.8-11.7 km) in Winter 1 and Winter 2, respectively. Over 75 percent (13) of 17 fish monitored remained within 5 km of their origination location. Valdez and Masslich (1989) concluded that, like adult Colorado squawfish, adult razorback suckers in the Green River probably ovecwinter within reaches 2 to 5 km long. Adult razorback suckers also showed a fidelity for specific overwinter locations. One razorback sucker, radiotagged and monitored in Rainbow Park (RM 327-328) on October 28, 1986, was recaptured at a suspected spawning area (Razorback Bar, RM 311), about 25 km downstream in April, 1987 (Personal Communication, Harold Tyus, U.S. Fish and Wildlife Service, November 1987). The fish was relocated, via radiotelemetry, in the same eddy complex (RM 327.3) over 13 months later on December 4, 1987, and monitored near this site until the radiotransmitter failed on March 24, 1988. This fish apparently traversed Split Mountain Canyon to and from the spawning area. A different adult razorback sucker was radiotagged near Mitton Park (RM 344.1) on October 27, 1986, and relocated aearly 16 months later, on February 19, 1988, about 2 km downstream. Valdez and Masslich (1989) suspected that other adult razorback suckers and Colorado squawfish would have been relocated at specific wintering sites, had the radiotransmitters lasted a full year. Adult razorback suckers, like adult Colorado squawfish, were locally active throughout winter. Movement was typically within a given habitat (e.g., slow run or slackwater), between several favorite spots. Local movement by overwintering razorback suckers was characterized by rates of 25 and 31 m/hr, for Winter 1 and Winter 2, respectively. This movement was usually between microhabitats that the fish occupied for extended periods of time. One fish (#OR-3257) monitored for 24 hours occupied three spots for periods of 15, 4, and 5 hours (Figure 13). The fish moved a total of 103 m, with net displacement of only 20 m from the original location. These movement rates were considered normal, and did not differ with habitat types, as with Colorado squawfish, i.e., greater movement by squawfish in backwaters was attributed to foraging for small fish prey. Habitat Use Colorado Squawflsh Habitat used by radiotagged adult Colorado squawfish in the two winters (1986-87 and 1987- 88) differed in both the Green and Yampa rivers (Figure 14). Different habitat use for Green River fish was attributed to flow and ice conditions (Winter 1 with high flow and no ice, Winter 2 with low flow and ice), and different use by Yampa River fish was attributed to flows (Winter 1 with high flow, 24