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OBJECTIVE #1 <br />ASSESS TROUT GROWTH RESPONSE TO ELEVATED HYDROELECTRIC <br />WATER RELEASE TEMPERATURES <br />METHODS - OBJECTIVE #1 <br />Between 1979 and 1981, growth of fish was monitored by weighing and <br />measuring marked, known-age fish recovered during electrofishing surveys <br />at three river reaches -- Tailrace, Little Hole, and Browns Park (Figure <br />1). Because growth estimates taken from creeled fish may be biased by <br />angler selectivity, especially among fish of smaller sizes, length-weight <br />data taken during creel surveys were not used to assess growth, except <br />during the 1963-1970 period, when electrofishing gear was not available. <br />Growth was estimated for known-age fish only. The rainbow and <br />cutthroat trout fishery was sustained almost entirely by stocking. <br />Fingerlings (approximately 100 mm total length) were marked prior to <br />stocking with a colored (red, green or yellow) granular fluorescent <br />pigment applied with a compressed air sprayer at the hatchery, as in <br />Phinney et al. (1967). Rainbow trout of catchable size (approximately <br />250 mm) were also stocked in the tailwater; although these were marked by <br />fin clipping, fish stocked as catchables were not used in estimating <br />trout growth. Brown trout were present in the tailwater, but this <br />species was sustained by instream recruitment and known-age fish were not <br />available. No attempt was made during this study segment to back- <br />calculate brown trout growth. <br />-15-