Genetic Considerations in Recovery Efforts for Pacific Salmon

The last few years have provided abundant indications that populations of all species of Pacific salmon (Oncorbyncbtrs spp.) are in decline. NeNsen et al. (1991) identified over 200 stocks they considered to be a t , some risk of extinction and over 100 already bdlieved to be extinct. llajor federal stock restoration programs are under way in the Columbia and Klamath River basins, and several populations of Pacific salmon have recently been listed as threatened or endangered under the U.S. Endangered Species Act (ESA). Although there is widespread agreement that recovery programs are needed for Pacific salmon, there is less agreement over what constitutes recovery. Recovery is commonly perceived as simply increasing overall abundance to a level commensurate with the needs of society. Here, the cerm recovery will be used to refer to restoration of viable! self-sustaining populations in their natural habitats. Lf this type of recovery is to be successful in the long run? it is essential to conserve the genetic resources which are the foundation of natural production. Notably, the Northwest Power Planning Council has recently modlfied its original goal of doubling overall run sizes in the Columbia River basin to the dual goal of increasing production while allowing no irreversible loss of genetic resources. How then to best conserve genetic resources during salmon recovery efforts? Although considerable advances have been made in the conservation genetics of salmonids during the last two decades, there is still much to be learned. For e.xample, the genetic basis for most phenotypic and life history variation-including traits that are likely to be among the most important in determining fitness-is complex and poorly understood, and there is little prospect for major advances in our understanding in the near future. Fortunately, it is not necessary to achieve a complete understanding of genetics to make substantial progress toward restoration of salmon populations. Recovery can be accomplished most eff~:ctively through comprehensive and timely measures to address the factors that may be impeding natural recovery, such as habitat destruction, blockage of migratory routes, overharvesting, and artificial propagation. If these factors are addressed properly, most stocks should recover naturally, and the major genetic issues will largely take care of themselves. Furthermore. if the root causes of decline of salmon