Movements, growth, age structure, and condition of rainbow trout, brown trout, and interior Dolly Varden in the lower McCloud River, California, were studied in the summer of 1974, in order to determine the best management strategy for a section of stream previously closed to the public, and containing trout populations unique to California. The population of native rainbow trout was found to be largely resident, while the non-native brown trout spent only the first 2 or 3 years of their life in the river before migrating downstream to Shasta Reservoir. Brown trout return to spawn at age IV and older. Growth in the river for both species is somewhat slow compared to other populations in the western United States, but growth in the reservoir for brown trout is rapid. Both species have condition factors typical for the species and both experience mid-summer depressions in condition, apparently related to reduced food availability. Dolly Varden were found to be extremely rare and only two fish were examined. It is likely that the Dolly Varden is non-migratory and slow-growing in the McCloud River. Following the study, special angling regulations were adopted to preserve the integrity of the native trout populations. Future management needs are discussed.
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