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<br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I, <br /> <br />I <br /> <br />1 <br /> <br />I <br />I <br /> <br />I <br /> <br />I <br />I <br /> <br />I <br />1 <br /> <br />I <br /> <br />I <br />1 <br /> <br />3a2~12 <br /> <br />loss may remain the same. We simply don't know and this information <br />would be extremely difficult to obtain. <br /> <br />It appears the small percentage of kokanee that migrate to deeper <br />depths during the day may be more susceptible to entrainment. During <br />the night, 93 percent of the fish were found at depth shallower than <br />30 M. However, during the day we detect >30 percent of the fish at <br />depths greater than 30 M. This diel migration pattern is commonly <br />observed for young kokanee sockeye) (Pella 1968). <br /> <br />Water profile velocities in the intake channel July 1996 (Vermeyem and <br />Wahl, 1996) indicated a water withdrawal zone between depths of 25 and <br />50 meters from the surface. The velocities ranged from 6 to 16 (~ 4) <br />cm/sec. Also indicated in this report was that larger acoustic <br />reflectors, interpreted as fish, were concentrated at 2 depths, 20 to <br />25 meters and 40 to 50 meters which is similar to data collected with <br />the hydroacoustic fish surveys. The velocity profiles were all <br />performed during the daylight hours. <br /> <br />Physical entrainment velocities could be responsible for the larger <br />numbers entrained during the highest discharge flows, but we also <br />speculate that young kokanee may be more suspectable to entrainment <br />during feeding, or simply more prone to migrate downstream. Juvenile <br />kokanee are visual feeders, requiring light to see their prey (Breet <br />and Groot, 1963). Possibly young fish are less attentive of their <br />location while actively searching for the zooplankton in the water <br />column. <br /> <br />Regardless of time of day, the vast majority of young kokanee are <br />found in the upper water column. Acoustical surveys have shown this is <br />where the highest densities of young kokanee are found. While this <br />has little direct bearing on this study, it does suggest that <br />significant numbers of these fish might be more vulnerable to <br />transport during surface reservoir spills or through the intake tower <br />during low reservoir elevations. During the past seven years, no <br />water has been released through the Blue Mesa spillway works (Floyd <br />Ostler, Bureau of Reclamation, Salt Lake City, personal communique) . <br /> <br />28 <br />