Review of Relative Fitness of Hatchery and Natural Salmon;Technical memo

摘要

To determine the status of natural anadromous salmonid populations with respect to the Endangered Species Act, the viability of these populations must be estimated. Deriving natural population viability estimates is made more difficult by the presence of hatchery-produced anadromous salmonids, which occur in large numbers throughout the Columbia River basin. First, in some cases the number or fraction of the population that represents hatchery fish may be unknown, either due to lack of monitoring or inadequate marking of hatchery fish. Second, even in cases where the number or fraction of hatchery fish is known, it is necessary to know or estimate the relative fitness of the hatchery fish compared to the natural fish in order to estimate the natural productivity of the population. The objectives of this technical memorandum are to summarize information on the relative fitness of hatchery and natural Pacific (Oncorhynchus spp.) and Atlantic salmon (Salmo salar), steelhead (O. mykiss), and brown trout (S. trutta), and to determine if there are any general patterns relating the origin and history of hatchery stocks to their relative fitness. Part of the motivation was to provide information that would be useful in updating the 2000 Federal Columbia River Power System (FCRPS) Biological Opinion. Since that biological opinion was written, numerous additional studies on the relative fitness of hatchery fish have been published in both the peer-reviewed and gray literature.