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DRAFT Larval drift may be an important part of the Colorado squawfish's life cycle (Tyus 1986) and laboratory studies indicate that "drift" may be active rather than a passive response to water current (Paulin et al. 1989). Larval squawfish drift downstream after hatching in the Green and Yampa rivers and rear in reaches of the river that are different from those in which spawning occurred (Haynes et al. 1984; Tyus 1986; Tyus and McAda 1984; Tyus et al. 1987). However, distribution of larval and post-larval squawfish in the Colorado River suggest that larvae in that subbasin may not drift long distances between known or suspected spawning and rearing areas (Archer et al. 1985). The most important rearing area in the Colorado River for young-of--the-year Colorado squawfish is between Moab, Utah, and the confluence with the Green River (RK 0-96 [RM 0-60]) (Archer et al. 1985). Other nursery areas in the Colorado River have been found: (1) in the upper Professor Valley (RK 112-129 [RM 70-81]); (2) between the confluence with the Dolores River and Westwater Canyon (RK 144-175 [RM 90-109]); (3) between Black Rocks and Loma (RK 225-241 [RM 140-150]), and (4) downstream-from the confluence with the Gunnison River (RK 257-273 [RM 160-170]). No larval squawfish have been found in the White River. Kaeding and Osmundson (1987) reported the capture of a single larval squawfish in the lower 3 km (1.9 miles) of the Gunnison River. In 1987, a total of 18 young-of-the-year Colorado squawfish were captured in the San Juan River at various locations. These fish were collected from backwaters of the river: two were taken from the area downstream of Shiprock, New Mexico, at RK 222 (RM 139) and RK 228 (RM 143); six near Bluff, Utah, at RK 150-161 (RM 94-101); and 10 were taken in the lowermost 38 river kilometers immediately upstream from Lake Powell. An additional young-of-the-year also was taken from this lowermost river area in 1988, collected from backwaters at RK 18 (RM 11). In 1990, a young-of-the-year Colorado squawfish was collected. from backwaters near 8iuff, Utah (Bill Bates, Utah Division of Wildlife, pers. comm.). Colorado squawfish were first successfully propagated at Willow Beach National Fish Hatchery in 1974. Progeny have since been obtained by both artificial and natural-spawning (Hamman 1981; Toney 1914). Wild Colorado squawfish obtained from the Green and Colorado rivers in autumn 1919 spawned over filter gravel in raceways. Wild-caught and hatchery-produced broodstock at Dexter National Fish Hatchery, New Mexico, spawned in May and June after an injection of pituitary extract; production was primarily limited by the physical constraints of the facility for holding and growing young (Hamman 1986). Growth As with most fishes, Colorado squawfish growth rates are variable and dependent upon water temperature, food, water quality,-age, and numerous other parameters. Tyus (1988) reported that the growth rate of 59 tagged-and recaptured adult fish in the Green River averaged 10.2 mm/yr (.4 in./year). Vanicek and Kramer (1969) back-calculated mean total lengths at annulus 11