Dispersal and abundance of hatchery-reared and naturally spawned juvenile Chinook salmon in an Idaho stream
juvenile, chinook, salmon, adult, Salmon River, hatchery, fingerlings, upstream, stocking, habitat
Journal or Book Title
North American Journal of Fisheries Management
The abundance and movement of naturally spawned fingerling Chinook salmon(Oncorhynchus tshawytscha) produced by transplanted adults and of hatchery-reared fingerlingChinook salmon was assessed in the Yankee Fork of the Salmon River, Idaho, during thesummer-fall rearing period. Adults and hatchery fingerlings were stocked in fall 1986 and spring1987, respectively, in the headwaters of the river. The highest densities of hatchery fingerlingswere located within 2.0 km downstream of release sites in all sampling periods. Little upstreammovement occurred. The highest densities of naturally spawned fingerlings were observed nearhigh concentrations of redds. Though the distribution patterns of both groups of fish remainedconstant throughout the summer, total abundance dropped dramatically. Total abundance inOctober was only 17% of early summer abundance. Hatchery fingerlings decreased inabundance in midsummer, 2-3 months after stocking, possibly due to premature out-migration.Timing of movement from the stream (normally in fall) may be related to fish size, so stocked fishshould be similar in size to naturally spawned fry. These results also indicate that fingerlingsshould be stocked at lower densities at more sites so that available habitat can be used moreeffectively.