AbstractCo-management theory argues that incorporating local knowledge into fisheries science decision-making can lead to more sustainable fisheries through improved fishery dynamics, reduced harvest pressure, and increased regulatory compliance. The Maine lobster fishery, Japanese fishing cooperatives, and Alaska’s Community Development Quota Program are all considered successful models of fisheries co-management. Co-management arrangements between Pacific Northwest treaty tribes and state managers were first established in the 1970s, following court decisions upholding the tribes’ treaty rights to fish. However, the long-term effectiveness of Pacific Northwest salmon fisheries co-management is not fully understood. Here I present an historical analysis of co-management effects for the Columbia River salmon fishery, from both an ecological and social perspective. My research objectives are to (1) evaluate the perceived impact of tribal participation in salmon fishery management decisions (2) assess social, economic, and ecological impacts of fisheries co-management, and (3) understand barriers to co-management efforts in terms of institutional and political frameworks. Building on Evelyn Pinkerton’s research, I use archival materials, scientific literature, and interviews with key actors to define key developments in Columbia River salmon fishery co-management, including legal decisions and the establishment of tribal fish commissions. I then conduct a preliminary analysis of co-management effectiveness over time. Initial results suggest that tribal participation in fisheries management has led to ecologically and socially sustainable fisheries management practices in the Columbia River basin, although political disagreements have held back progress. For example, tribal fisheries co-management has led to improved ecological management practices, including new requirements for counting fish harvest levels and monitoring of habitat quality. Co-management has created economic opportunities, such as niche markets for native-caught fish and added-value processing, which can generate larger profits from smaller fish harvests. Increasing tribal fisheries capacity through co-management has also forwarded community efforts to ensure cultural survival by maintaining traditional fishing practices. Institutional and political barriers to co-management that include sovereignty issues, regulatory conflicts, and funding needs present challenges to resolving habitat management problems for the region.