Current marine protected areas (MPAs) leave almost three-quarters of ecologically and functionally important species unprotected, concludes a new performance assessment of the Finnish MPA network. Published in Frontiers in Marine Science, the study finds the MPAs were designated with little knowledge of local marine biodiversity—and that increasing existing networks by just 1% in ecologically most relevant areas could double conservation of the most important species. In addition to identifying areas of high conservation value, the methodology—which uses a unique new dataset of 140,000 samples—can also be used in ecosystem-based marine spatial planning and impact avoidance, including siting of wind energy infrastructure, aquaculture and other human activities.