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1 1 1 1 1 1 1 1 and upstream migrations in the Green, White, and Duchesne rivers to spawn in riffle/pool habitat of the lower 32 miles of the Yampa Canyon. The only other confirmed Colorado squawfish spawning site exists in Gray Canyon of the Green River (Tyus et al. 1987). A total of 37 Colorado squawfish were radiotracked to the Yampa Canyon spawning ground by FWS (N=31) and CDOW (N=5) from 1981-1987. These included 23 fish from the upper Yampa River, 12 fish from the Green River, and one fish that migrated 233 miles from the White River. Migrants tracked by FWS averaged 78 miles one-way. The distance traveled by the White River fish may have exceeded one year since the fish was tagged at River Mile (RM) 103 White River in 1983, tracked to RI°I 31 Yampa River in spring 1984, and recaptured at RM 98 White River in 1935. These radiotracking data show that adult Colorado squawfish migrate to the Yampa Canyon (strata 1 and 2, Figure 3) in early summer from many areas throughout the upper Green River basin (including White, Green and Yampa rivers). These data also suggest that ali adult fish do not spawn each year. Of four fish radiotracked in consecutive years (1T years) during the spawning season, two did not migrate each year and remained in the same river reach. Local movements of these non-migrants may be indicative of home range behavior in nonbreeding years. Adult Colorado squawfish were radiotracked in early spring in the upper Yampa River by FWS in 1981 and 1983 (Tyus and McAda 1984, Tyus 1985), and by CDOW/NPS in 1982 (Wick et al. 1983). These fish initiated spawning migrations from 12 May to 10 June, depending on type water year (Table 1). Flow and water temperature conditions were highly variable within each migration period and between years. However, it appears that spawning migrations were initiated earlier in low water years (e.g. 1981) and later in higher water 11