Scholars of common property resource theory (CPR) have long asserted that certain kinds of institutional arrangements based on collective action result in successful environmental stewardship, but feedback and the direct link between social and ecological systems remains poorly understood. This paper investigates how common property institutional arrangements contribute to sustainable mangrove fisheries in coastal Ecuador, focusing on the fishery for the mangrove cockle (Anadara tuberculosa and A. similis), a bivalve mollusk harvested from the roots of mangrove trees and of particular social, economic, and cultural importance for the communities that depend on it. Specifically, this study examines the emergence of new civil society institutions within the historical context of extensive mangrove deforestation for the expansion of shrimp farming, policy changes in the late 1990s that recognized "ancestral" rights of local communities to mangrove resources, and how custodias, community-managed mangrove concessions, affect the cockle fishery. Findings from interviews with shell collectors and analysis of catch-per-unit-effort (CPUE) indicate that mangrove concessions as common property regimes promote community empowerment, local autonomy over resources, mangrove conservation and recovery, higher cockle catch shares, and larger shell sizes, but the benefits are not evenly distributed. Associations without custodias and independent cockle collectors feel further marginalized by the loss of gathering grounds, potentially deflecting problems of overexploitation to "open-access" areas, in which mangrove fisheries are weakly managed by the State. Using Ostrom's Institutional Analysis and Development (IAD) framework, the explicit link between social and ecological systems is studied at different levels, examining the relationship between collective action and the environment through quantitative approaches at the fishery level and qualitative analysis at the level of the mangrove landscape. Implications for coastal and fishery management are discussed in the conclusions.
