Protecting the global ocean for biodiversity, food and climate

The ocean contains unique biodiversity, provides valuable food resources and is a major sink for anthropogenic carbon. Marine protected areas (MPAs) are an effective tool for restoring ocean biodiversity and ecosystem services1,2, but at present only 2.7% of the ocean is highly protected3. This low level of ocean protection is due largely to conflicts with fisheries and other extractive uses. To address this issue, here we developed a conservation planning framework to prioritize highly protected MPAs in places that would result in multiple benefits today and in the future. We find that a substantial increase in ocean protection could have triple benefits, by protecting biodiversity, boosting the yield of fisheries and securing marine carbon stocks that are at risk from human activities. Our results show that most coastal nations contain priority areas that can contribute substantially to achieving these three objectives of biodiversity protection, food provision and carbon storage. A globally coordinated effort could be nearly twice as efficient as uncoordinated, national-level conservation planning. Our flexible prioritization framework could help to inform both national marine spatial plans4 and global targets for marine conservation, food security and climate action

Reply to: A path forward for analysing the impacts of marine protected areas

[Extract] We appreciate the recommendations from Hilborn and Kaiser to further our analysis1, and although we agree with some of the suggestions in their Comment2 as a basis for future work, they do oversimplify and mischaracterize several of our conclusions. First, Hilborn and Kaiser2 comment on our assumptions about effort redistribution once marine protected areas (MPAs) are created. They suggest that we were inconsistent in our treatment of effort redistribution and that the benefits to biodiversity and carbon would be nullified under a full-effort transfer scenario; however, we disagree with this suggestion. The objective of our analysis was to identify the most beneficial areas to place MPAs, which are a commonly used tool to conserve biodiversity, help to recover fish stocks and can mitigate climate change3,4,5,6,7. We tested how the location of the most beneficial places would change under two different assumptions of how fishing effort relocates outside the MPA after implementation: (1) no effort is relocated and (2) all effort is relocated. The first assumption implies an overall reduction in total fishing effort as areas of the ocean get protected and we applied it consistently across the three objectives. We find that under this assumption, protecting 24% of the ocean would maximize benefits across all objectives if biodiversity and food provision are set to be equally important (figure 3 and supplementary figures 10 and 13 of ref. 1)