Introduction to marine managed areas

No issue in marine conservation and management seems to have generated as much interest, and controversy as marine protected areas (MPAs). In the past 30 years, a substantial scientific literature on the subject has developed, international agreements have set targets for proportion of the sea to be protected, and hundreds of millions of dollars have been spent on research and advocacy for MPA establishment. While the objectives of MPAs are diverse, few studies evaluate the success of MPAs against stated objectives. It is clear that well-enforced MPAs will protect enough fish from exploitation that within reserves abundance increases, fish live to be larger, and measures of diversity are higher. What is much more poorly understood is the impacts of reserve establishment on areas outside reserves. Theory suggests that when stocks are seriously overfished outside reserves, the yield and abundance outside the reserves may be increased by spillover from the reserve. When stocks are not overexploited, reserve establishment will likely decrease the total yield. The chapters in this volume explore a broad set of case studies of MPAs, their objectives and their outcomes.