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first captured on the spawning area have been recaptured later at other locations of the river system. Sampling conducted when radiotagged Colorado squawfish were present in the Yampa sJ,awning area has produced 89 ripe ad u1 t fish. The second area of concentrated spawning activity is in the Gray Canyon between RK 239-253 (RM 148-15 7). There is not as extensive a data base and period of record for this reach but 14 radio-tagged Colorado squawfish were tracked to the area during the spawning season from 1981 to 1984 and 38 ripe Colorado squawfish have been collected in this reach. Larval fish collections indicate successful spawning in this area since it is inconceivable that the lO-day old larva collected from downstream reaches would have drifted 300 m1 from the confirmed Yampa spawning area. Calculating drift rates from Haynes and Muth (1984) with the assumption that the older larva drifted from the upper end of the Yampa spawning reach and the youngest from the lower, drift rates between 1.2-2.6 m1 per day are suggested. Applying simUar calculations to 7 larva collected by CRFP during 1983 at RK 207 (RM 129.6) provides an estimated drift rate of .8-1.2 ini/day, assuming they were spawned at RM 155. Thus the largest larva (22.2 mm) collected by CRFP from the lower Green was an estimated 30 days old and would likely have been spawned below RK 268 (RM 166). There are several other reaches for which strong but less definitive evidence suggests that spawning is occurring in the Green. CRFP has observed radiotagged Colorado squawfish migrating to a number of areas (Table 1) and, though complicated by the presence of confirmed spawning areas upstream~ the collection of larval Colorado squawfish less than 22 days old in those areas lends credence to those conclusions. Colorado River spawning areas are not well defined because several radiotagged. fish have not been observed congregating in specific aTeas during the spawning season, however, the presence of larval Colorado squawfish throughout much of the system proves that spawning is occurring. 15