Ten years of dynamic co-management of a multi-species reef fishery

Co-management, a governance process whereby management responsibility is shared between resource users and other collaborators, is a mainstream approach for governing social and ecological aspects of small-scale fisheries. While many assessments of co-management are available for single time periods, assessments across longer time-scales are rare–meaning the dynamic nature, and long-term outcomes, of co-management are insufficiently understood. In this study we analyse ten-years of catch and effort data from a co-managed, multi-species reef fishery in Solomon Islands. To further understand social, ecological and management dynamics we also draw on interviews with fishers and managers that had been conducted throughout the same decade. We aimed to answer (1) what are the temporal trends in fishing effort, harvesting efficiency, and catch composition within and beyond a periodically-harvested closure (i.e. a principal and preferred management tool in Pacific island reef fisheries), and, (2) what are the internal and external drivers that acted upon the fishery, and its management. Despite high fishing effort within the periodically-harvested closure, catch per unit effort remained stable throughout the ten years. Yet the taxonomic composition of catch changed substantially as species targeted early in the decade became locally depleted. These observations indicate that both the frequency of harvesting and the volumes harvested may have outpaced the turnover rates of target species. We argue that this reflects a form of hyperstability whereby declining abundance is not apparent through catch per unit effort since it is masked by a shift to alternate species. While the community sustained and adapted their management arrangements over the decade as a response to internal pressures and some signs of resource changes, some external social and ecological drivers were beyond their capabilities to govern. We argue the collaborative, knowledge exchange, and learning aspects of adaptive co-management may need even more attention to deal with this complexity, particularly as local and distal pressures on multi-species fisheries and community governance intensify. Graphical abstract