Marine protected areas (MPAs) play a leading role in conserving and restoring marine environments. MPAs can benefit both marine populations within their boundaries and external populations owing to a net export of organisms (spillover). However, little is known about variation in performance within MPAs. For example, edge effects may degrade populations within MPAs close to their boundaries. Here we synthesize empirical estimates of 72 taxa of fish and invertebrates to explore spatial patterns across the borders of 27 no-take MPAs. We show that there is a prominent and consistent edge effect that extends approximately 1 km within the MPA, in which population sizes on the border are 60% smaller than those in the core area. Our analysis of cross-boundary population trends suggests that, globally, the smallest 64% of no-take MPAs (those of less than 10 km² in area) may hold only about half (45–56%) of the population size that is implied by their area. MPAs with buffer zones did not display edge effects, suggesting that extending no-take areas beyond the target habitats and managing fishing activities around MPA borders are critical for boosting MPA performance.

海洋保护区 (MPA) 在保护和恢复海洋环境方面发挥着主导作用。由于生物体的净输出（溢出效应），海洋保护区既有利于其边界内的海洋种群，也有利于外部种群。然而，人们对海洋保护区内绩效的变化知之甚少。例如，边缘效应可能会降低 MPA 内靠近其边界的种群数量。在这里，我们综合了 72 个鱼类和无脊椎动物类群的经验估计，以探索跨越 27 个禁捕海洋保护区边界的空间格局。我们表明，在 MPA 内延伸约 1 公里处存在突出且一致的边缘效应，其中边界的人口规模比核心区域的人口规模小 60%。我们对跨境人口趋势的分析表明，在全球范围内，²的面积）可能只占其面积所暗示的人口规模的一半左右 (45–56%)。具有缓冲区的 MPA 没有显示出边缘效应，这表明将禁捕区扩展到目标栖息地之外并管理 MPA 边界周围的捕鱼活动对于提高 MPA 性能至关重要。