Release of captively reared adult salmon for use in recovery

摘要

In recent years the philosophy of salmon management in the Pacific Northwest has been changing from one that justifies hatchery production solely on fishery harvest to one that conserves and enhances natural populations. Imperiled salmon Oncorhynchus spp. populations are increasingly being brought into captivity for stock conservation or recovery. The emphasis on conservation is largely in response to the alarming numbers of salmon populations facing extinction risk in the Pacific Northwest. The new conservation philosophy requires integration of hatchery and natural production. Consequently it has become a major focus of fisheries research. Conservation hatcheries are designed to rebuild or maintain natural spawning populations. Therefore, theirculture strategy is to raise fish, which will successfully reproduce, and integrate closely with the free-ranging wild stock. Captive broodstocks of Pacific salmon are being maintained as part of the conservation hatchery concept. These programs differ from traditional hatchery programs in one important respect: fish are cultured in captivity for their entire life cycle. Their benefit for conservation is that they bypass the typically high natural smolt-to-adult mortality, making them an appealing toolfor the recovery of threatened or endangered species, or for short-term supplementation of natural populations. With the high fecundity of Pacific salmon and potentially high survival in protective culture, captive broodstock programs afford an opportunity to produce large numbers of juveniles or adults for reintroduction in a single generation (Schiewe et al. 1998).