ABSTRACT
Alask’s salmon ocean ranching program began in the mid-1970s as an effort to develop sustainable fisheries after more than 25 years of frequent run failures. The failures were attributed to the effects of severe winters on embryo survival, particularly of pink and chum salmon Onco-rhynchus gorbuscha, O. keta. Thirty-nine hatcheries, mostly run by private, non-profit corporations, now release over 1 billion fry and smolts, producing 25–50 million harvested salmon annually. A mark of the program’s success is that some regional fisheries depend on hatchery-produced salmon in years when, or places where, wild stocks cannot be harvested. Protection of wild stocks is the first priority of fishery managers. Risks to wild stocks associated with the program, primarily of excessive harvest in mixed fisheries, of genetic introgression and lost fitness, and of disease dissemination, have been identified, addressed, and reduced (but not eliminated) throughout the history of the program. Tags and marks on hatchery-produced salmon have been used during annual harvests to discriminate wild salmon. These have included coded wire tags and recently mass-marking of hatchery salmon through otolith thermal marking; they have been used to provide managers of mixed stock fisheries with precise information about the relative abundances of hatchery and wild salmon during fishing seasons. Management of wild stocks in some instances has been made easier by diversion of fishing effort to hatchery stocks. Many releases of cultured salmon have been prohibited where interactions with significant or unique wild stocks were foreseen. Nearly all transfers of salmon into Alaska or between regions of Alaska have been prohibited. Strict disease-prevention inspections have been required before transplants within regions have been permitted. Risks associated with ecological interactions between Alaska hatchery salmon and wild salmon in the marine environment are potentially important but these interactions have not been detected.
