Northwest Fisheries Science Center (U.S.)

Local extirpations of Pacific salmon, often due to dams and other stream barriers, are common throughout the western United States. Reestablishing salmonid populations in areas they historically occupied has substantial potential to assist conservation efforts, but best practices for reintroduction are not well established. In this report, we present a framework for planning reintroductions designed to promote recovery of salmonids listed under the Endangered Species Act. Prior to implementation, managers should first describe the benefits, risks, and constraints of a proposed reintroduction. We define benefits as specific biological improvements toward recovery objectives. Risks are potential negative outcomes of reintroductions that could worsen conservation status rather than improve it. Constraints are biological factors that will determine whether the reintroduction successfully establishes a self-sustaining population. We provide guidance for selecting a recolonization strategy (natural colonization, transplanting, or hatchery releases), a source population, and methods for providing passage that will maximize the probability of conservation benefit while minimizing risks. Monitoring is necessary to determine whether the reintroduction successfully achieves the benefits, and to evaluate impacts on nontarget species or populations. Many of the benefits, especially diversity and the evolution of locally adapted population segments, are likely to accrue over decadal time scales. Thus, we view reintroduction as a long-term approach to enhancing viability.

http://doi.org/10.7289/V5/TM-NWFSC-141

Technical Memorandum