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I I I I I I I I I I I I I I I I I I I 15 km in only a few weeks. Changes this rapid undoubtedly influence the distribution and reproductive cycles of non-native predators, and might be manipulated to regulate predator densities. If successful, present programs to augment spawning cohorts in either the San Juan, Green, or Colorado rivers will result in larval sucker transport into Lake Powell. With the general absence of nursery habitat in the lower 100 km reach of these rivers, natural recruitment associated with these portions of the river might be largely dependent upon nursery habitat found either further upstream, or downstream, in Lake Powell. Manipulation of reservoir elevations may provide the greatest chance for these, and other, young natives to survive. The concept certainly deserves more evaluation. RECOMMENDATIONS The behavioral acclimation test suggests that holding fish on site for 3 days may influence their dispersal rate. We recommend further testing be conducted to confirm this in both reservoir and riverine habitats. We recommend that external attachment techniques be considered by other researchers when studying the short-term movements and behavior of the razorback sucker and other similarly keeled, Colorado River fishes. This approach is less intrusive than surgery, non-lethal, and possibly best suited for juveniles or wild fish. Juveniles have a strong fidelity toward shoreline habitats which are also used by known predators such as largemouth bass and channel catfish (Harlan and Speaker 1951, Tyus 1997). This habitat attraction may help explain the virtual absence of young razorback suckers. We recommend that further research be directed at developing and evaluating methods of reducing or eliminating predation. Current efforts to augment existing population by stocking larger razorback suckers does not address the problems of early life stage survival. We also need to better understand non-native predator effectiveness, and explore methods that might reduce or minimize predator densities found in habitats used by early life stages of razorback sucker. Until more information is available, we suggest that larger (> 30-cm) fish be stocked and that stocking be delayed until winter when predators are dormant (Marsh and Brooks 1989). Predation concerns stemming from assessed survival rates has resulted in a recommended stocking size of 40-cm for augmenting San Juan River stocks (Ryden 1997a). We support this approach. 17