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Flow Chamber Trials We set up the experiment so that we evenly paired treatments; for example, we would test a 22- em control fish and then a 22-cm exercised fish. We compared the cumulative distribution function of critical flow velocities (UcrJ between exercised and unexercised razorback suckers using a Kolmogorov- Smimov two-sample test that provides information on maximum differences within the distributions, and the MRPP two-group comparison that focuses on average deviations. These nonparametric methods were used to test the hypothesis that exercised fish would handle critical flow velocities better than unexercised fish. Results Exercise Treatment Razorback Sucker Exercised groups exhibited no sign of fatigue or stress. They roamed freely during exercise periods, easily navigating the velocity. They generally formed a large school that preferred the most upstream site near the motor and the downstream bend. Suckers in all four tanks typically schooled along the bottom of the tank during daylight hours, but they would disperse throughout the water column when the current was turned off at night. Bonytail The two die-offs of bony tail were disappointments but not a surprise. We had been warned by hatchery personal that these fish are extremely susceptible to stress-related disease. However, we do not believe the exercise regimen in itself caused the mortality, but undoubtedly contributed to it. Three healthy bony tail were discovered among the exercised razorback suckers that had endured 20 weeks of flow; in addition, flow chamber results suggest bony tail are strong swimmers. Hatchery personnel reported the exercised bony tail quit feeding once the exercise regimen started. It has been reported (Mueller, 2006) that bony tail are nocturnal, and possibly the fish needed to be exercised at night rather than during the day. That combines with other existing stressors (for example, crowding and spawning season) that might have triggered chronic fatigue, leaving exercised fish more susceptible to the outbreak of ich. A similar outbreak of ich occurred at the end of our 2007 field season, which claimed all the remaining (> 150) control bony tail. Predator Exposure Razorback Suckers-2006 Efforts Impromptu Tank Experiments In trial 1, the two flathead catfish and 10 razorback suckers co-existed in the tank experiment for seven days without predation occurring. Based on daytime observations, razorback sucker used both sides of the tank; 46 percent of the prey counted were found with the flathead catfish (n = 20). There was no evidence of predator avoidance by razorback suckers (fig.6; Appendix B). 9