Historical Population Structure of Coho Salmon in the Southern Oregon/Northern California Coasts Evolutionary Significant Unit

The main purpose of technical recovery planning for Pacific salmon and steelhead is to produce biologically based viability criteria for listed Evolutionarily Significant Units (ESUs) that will be considered in setting recovery goals. These viability criteria, and the analyses from which they stem, must refer to specific populations and population groups (i.e., populations or groups of populations within a ESU). The purpose of this report is to describe the historical population structure of coho salmon in the Southern Oregon/Northern California Coast (SONCC) ESU in order to guide viability analyses, and to provide a historical context for other parties interested in recovering coho salmon in the geographic region. We collected and examined available information relevant to the question of population structure of coho salmon in the SONCC ESU, and we present that information here.