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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 />I <br />I <br />I <br /> <br />I <br />I <br /> <br />I <br />I <br /> <br />I <br />I <br /> <br />I <br /> <br />I <br /> <br />OD(~~6 <br /> <br />to their ability to feed in warmer, shallower, more productive areas <br />of the lake. This might help explain a marked decrease (85% to 50%) <br />in the percentage of small fish detected in deeper and colder pelagic <br />habitats. This feeding behavior and distribution are quite common <br />(Groot & Margolis 1991). <br /> <br />June and October surveys provide valuable information on distribution, <br />however, fish were more widely distributed through the water column. <br />Undoubtedly, some fish found in the shallower habitats were not <br />detected, nor included in the estimates. This also applies to the <br />October estimates when the reservoir was cooling. <br /> <br />October density measurements were approximately half of the levels <br />measured in June and August. This decline, combined with a decline in <br />the percentage (40% to 18%) of large fish detected, suggests the <br />possible influence of angler harvest and the movement of mature <br />spawners into tributaries and shallower water. These, and other <br />factors, by themselves, or in conjunction with other factors, could <br />explain the data. <br /> <br />We are confident of the fish density measurements taken in the pelagic <br />zone of the reservoir. population estimates closely coincide with <br />similar, but independent estimates developed by CDOW (Martinez 1995). <br />Pelagic population estimates are undoubtedly conservative and do not <br />in the true sense represent "reservoir population estimates." The <br />surveys were specifically designed to focus on kokanee and were not <br />meant to represent other species found in the reservoir's littoral <br />zone. The inclusion of shallower portions of the reservoir in these <br />surveys is possible, however, survey techniques would have to be <br />modified. <br /> <br />Recoll\lllendations <br /> <br />The study thus far has provided a substantial amount of valuable <br />information. An effective sieve net program was developed that <br />provided the first verifiable information pertaining to fish passage. <br />Additional work is needed regarding fish passage under a wider range <br />of reservoir operations and runoff conditions. The most expensive <br />aspect of the project (design, installation, testing) has been <br />completed, additional data could be collected very efficiently. We <br />recommend sieve net sampling be continued for at least 5 years during <br />the initiation of flow criteria. A cost-effective program could be <br />developed using local personnel to operate the net. This option <br />should be considered by Reclamation, NPS, and eDOW. <br /> <br />32 <br />