Productivity of Alaska's Salmon Hatchery Ocean Ranching Program and Management of Biological Risks to Wild Pacific Salmon

Abstract

Modern salmon hatcheries in Alaska were established in five regions of the state in the 1970s, when wild runs of salmon were at record low levels. Initially conceived as a state-run system, the Alaska program has evolved in the private sector and is centered on private, non-profit, regional aquaculture associations run by fishermen and other stakeholders. Presently, Alaska has 33 production hatcheries (14 hatcheries have closed). Many release over 100 million young salmon annually; between 1.3 and 1.4 billion are released in total. In 1975, hatcheries produced fewer than 20,000 adult salmon. During the 1990s, the Alaska program produced 27-54 million adult salmon annually, which accounted for 14-37% of the annual common-property salmon harvest. It is second in size and productivity to the Japanese ocean ranching program (approximately 2 billion fry released annually, 50-70 million salmon harvested). Pink salmon (Oncorhynchus gorbuscha) and chum salmon (O. keta), which are species released into the oceanic environment as postlarvae, comprise >80% of the hatchery production. Protection of wild-salmon fitness and rigorous evaluation of hatchery contribution to fisheries have been emphasized throughout the development of the Alaska ocean ranching program. Strict regulation by public-agency geneticists, pathologists, and fishery managers of hatchery siting, hatchery capacity, and transport of salmon between streams has reduced risks to wild-salmon fitness. Recent implementation of mass-marking technology has enabled harvest managers to protect wild salmon in mixed-stock fisheries from unsustainable fishing mortality. Both hatchery and wild stocks have experienced high marine survivals since the late 1970s, resulting in record salmon harvests through the 1990s.