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' period in 1987, may indicate an effort to move to spawning areas, perhaps areas immediately below or somewhere above the respective dams. Alternative- ly, movements of some fish to these sites, especially movements well after the spawning period, may indicate that dam plunge pools are good feeding and resting habitat sought by Colorado squawfish during low summer flows. ' Percent species composition of Colorado squawfish in larval samples taken ' during 1986 was very similar between the 18-mile and Gunnison reach collections (Table 6). In 1987, squawfish percent composition in samples ' was considerably less than in 1986. This observation and that of the difference in mean catch per effort of YOY between years (4.02 vs 2.75/100 ' m2) in the lower 18-mile reach suggests that 1987 was not a particularly ' good year for squawfish reproduction in the Grand Valley. Razorback Sucker Razorback suckers spawn in the Grand Valley area in May and June, the ' precise period being determined by water temperature, photoperiod and perhaps other environmental variables. Because razorback sucker are so rare and our data on radio-tagged razorbacks is relatively limited, it is ' difficult to draw definitive conclusions about their movement patterns. A ripe razorback captured from the 15-mile reach on 3 June 1986 and given a ' radio tag at that time spent the remainder of the year at a location 10.7 miles downstream. Another razorback captured in the 15-mile reach on 11 ' June 1987 similarly spent the remainder of the year at a location 12 miles ' downstream (RM 166.5). A third razorback tagged on 19 May at RM 168.2 (2.8 miles below the 15-mile reach) was located on June 8 in the 15-mile reach, ' seven miles upstream from its point of release. The fish subsequently returned to within 1.3 miles of its release site. These results suggest ' 20