Framework for Assessing Viability of Threatened Coho Salmon in the Southern Oregon/Northern California Coast Evolutionarily Significant Unit

This report describes a framework for assessing coho salmon population viability that includes developing objective, measurable criteria that when met, would define when the Southern Oregon/Northern California Coast Coho Salmon Evolutionarily Significant Unit (ESU) is naturally self-sustaining with a low risk of extinction. Technical recovery planning for Pacific salmon and steelhead is intended to produce biologically based viability criteria for listed ESUs that will be considered in setting recovery goals. The listing unit for Pacific salmon is the ESU. ESUs are defined as a population or group of populations that are substantially reproductively isolated from other conspecific population units and that represent an important part of the evolutionary legacy of the species. The Southern Oregon/Northern California Coast (SONCC) Coho Salmon ESU includes coho salmon populations from Elk River (Oregon) in the north to Mattole River (California) in the south. This report provides a framework to assess the viability of individual populations within this region and describes the spatial configuration of viable independent populations and dependent populations that would lead to a high likelihood of long-term ESU persistence. This report constitutes a technical recommendation by the TRT intended to assist recovery planners in developing recovery strategies and prioritizing recovery actions. It does not constitute official agency policy.