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flows and ice conditions. Ten fish were monitored in the Green River from December through March, 1986-87 (Winter 1), and ten different fish were monitored from December through March, 1987-88 (Winter 2) (Valdez and Masslich 1989). Similarly, ten adult Colorado squawfish were radiotagged and simultaneously monitored in the Yampa River during each of the same time periods (Wick and Hawkins 1989). Ten adult razorback suckers were also radiotagged and monitored in each of the two winters in the Green River. Radiotagged fish were periodically located during regular monthly trips in the 4-month winter period. Location, movement, and habitat use were recorded for -each relocated fish, and each fish was monitored for periods of one to several days to determine local activity, and response to flow change and ice conditions. Movement and activity of the Green River fish and the Yampa River fish (Table 3) are compared in the following discussion. Table 3. Winter movement (average net movement in kilometers) by radiotagged adult Colorado squawfish and razorback suckers in the Green River and Yampa River (from Valdez and Masslich 1989, Wick and Hawkins 1989). Green River Fish Yampa River Fish Fish Species Winter 1 Wlnter 2 Winter 1 Winter 2 Colorado squawfish 9.0 5.8 0.5 0.8 Razorback sucker 3.4 4.7 - - Fish Movement And Activity Colorado Squawflsh Radiotagged adult Colorado squawfish moved relatively little during the two winters observed in the Green and Yampa rivers. Common use of areas in winter, and return to specific locations a year later suggests homing and fidelity for overwintering locations and habitats in both rivers. Average net movement (distance from first to last radio contact) of the Green River fish was 9.0 km (n=10, range of 0.2-35.7 km) and 5.8 km (n=9, range of 0-41.7 km) during Winter 1 and Winter 2, respectively. Excluding the fish with greatest movement, average net movement was 6.0 km (n=9, range of 0.2-22.4 km) and. 1.3 km (n=8, range of 0.0-3.2 km), respectively. Nearly 80 percent (15) of 19 fish monitored remained within 5 km of their original location. Movement by the Yampa River fish under ice cover averaged 0.5 km each year, with ranges of 0.0 to 1.8 km in Winter 1, and 0.0 to 0.8 km in Winter 2. Lesser movement by the Yampa River fish may be explained by distribution of habitat in the two rivers, and more stable flows and ice conditions. The Yampa River 21