|Document Type:||Journal Article|
|Title:||A synthesis of findings from an integrated hatchery program after three generations of spawning in the natural environment|
|Author:||D. E. Fast, Curtis M. Knudsen, W. J. Bosch, A. L. Fritts, G. M. Temple, M. V. Johnston, T. N. Pearsons, Donald A. Larsen, Andrew H. Dittman, D. May, C. R. Strom|
|Journal:||North American Journal of Aquaculture|
The Cle Elum Supplementation and Research Facility in the Yakima River Basin (Washington State, USA) is an integrated spring Chinook Salmon Oncorhynchus tshawytscha hatchery program designed to test whether artificial propagation can increase natural production and harvest opportunities while keeping ecological and genetic impacts within acceptable limits. Only natural-origin fish are used for hatchery broodstock. Spawning, incubation, and early rearing occurs at a central facility; pre-smolts are transferred for final rearing, acclimation, and volitional release at sites adjacent to natural spawning areas where returning adults can spawn with natural-origin fish. The first wild broodstock were collected in 1997 and age-4 adults have returned to the Yakima River since 2001. An unsupplemented population in the adjacent Naches watershed provides a reference for evaluating environmental influences. The program has been comprehensively monitored from inception. A synthesis of findings, many already published, includes: supplementation increased harvest, redd counts, and spatial distribution of spawners; natural-origin returns were maintained; straying to non-target systems was negligible; natural origin females had slightly higher breeding success (production of surviving fry) in an artificial spawning channel, while behavior and breeding success of natural- and hatchery-origin males were similar; hatchery-origin fish showed differences in morphometric and life history traits; high rates of hatchery age-2 (mini-jack) production were reported but observed proportions of outmigrating juvenile and adult (ages 4 and 5) returning males were comparable for hatchery and natural-origin fish; hatchery smolts did not affect levels of pathogens in natural smolts; and, ecological interactions attributed to the program were within adopted guidelines. Our results to date indicate that an integrated hatchery program using 100% natural-origin broodstock can increase harvest, return fish to the spawning grounds, and maintain natural abundance, with few apparent short-term impacts to the target ecosystem. Additional study is required to assess long-term impacts to natural production and productivity.