Steps to Supplementation Success
A comprehensive marking strategy was developed for Snake River fall Chinook hatchery programs. The mark strategy accounted for harvest mitigation, hatchery operation, and monitoring and evaluation. Fifty percent of the production is marked externally, 28% of the production is internally marked, and 22% is unmarked. Under this marking strategy, non-selective recreational and treaty harvest is occurring, natural-origin fish are being incorporated into the broodstock, and natural-origin abundance is being measured.
The Johnson Creek summer Chinook supplementation project was initiated to avert extirpation. Adult return management consisted of using only wild fish in the broodstock with no restrictions placed on hatchery fish escapement to spawning grounds. With the use of genetic based parentage assignment we documented a 30% increase of natural origin adult returns, an equal reproduction rate between naturally-spawning hatchery fish and wild fish, and fitness of the natural population was maintained.
Management of Lostine River spring Chinook salmon adult returns is guided by hatchery and harvest sliding scales. Allocation of adult returns is based on estimated abundance of wild returns and relative abundance of hatchery returns. Hatchery return disposition from this integrated mitigation/supplementation program has been 12% to consumption and 88% to conservation. Consumption consisted of harvest (6%) and distribution as food (6%). Conservation consisted of broodstock (6%), adult outplants to under-seeded habitat (7%), and natural spawning (75%).