Community based and co-management approaches are increasingly used strategies for marine conservation and sustainable management in the tropical Pacific. However, our understanding of the effectiveness of co-management on marine resources and socio economic conditions is relatively limited, often due to insufficient resources to support monitoring based on ecological condition or catch landings data. Monitoring programmes based on the perceptions of resource users are often presented as a cost effective alternative to understanding the status and changes in resource and socio economic conditions. Ecological, catch landings and perception-based data, and their collection methods, have different benefits and limitations for community-based programmes. Here we present a study of the first community-based, co-managed area in the Kingdom of Tonga - the small island of 'O'ua. We examine both perception-based data from interviews and catch landings data to describe fishing activities, catches and changes in resource status and socio economic conditions since the inception of co-management. Landings data were collected by the community over a five year period; perceptions of change and management performance were collected through structured interviews with fishers based on the same time period.