More than 100 countries worldwide have pledged to protect at least 30% of the ocean by 2030, covering both national waters and the high seas. But where should protection be focused to best conserve marine biodiversity? Recent research suggests the key lies in identifying and prioritizing a small but critically important 1% of the ocean, called “consensus marine zones.” Dr. Qianshuo Zhao from Ocean University of China and Professor Mark John Costello from the University of Bergen, Norway, published a study in Trends in Ecology & Evolution analyzing multiple independent global marine biodiversity studies. They mapped these consensus zones for the first time, showing that protecting just 1% of the ocean could shelter half of all marine species.
Despite the growth of Marine Protected Areas (MPAs) worldwide, over half are not located in global biodiversity priority regions. Traditional national or regional planning often misses the global distribution of species, leading to inefficient protection. Many existing MPAs still allow fishing, failing to effectively conserve biodiversity. Most IUCN categories focus on “natural features” rather than biodiversity itself. Only IUCN Category I (strict nature reserves) and some Category II (national parks) maintain species in their natural state. Since the “30 by 30” goal focuses on biodiversity, only these categories meet the standard.
Systematic conservation planning is considered best practice. It uses data-driven methods to maximize biodiversity representation within coherent ecological networks. Zhao and Costello analyzed six global studies covering species diversity, endemism, key biomes, and topography. Despite differences in methods, all studies highlighted the same 1% of ocean areas as critical for biodiversity protection.
These 1% “consensus zones” are scattered globally, including the Northeast Pacific seamounts, San Juan Bautista Island, offshore St. Louis, the central Mid-Atlantic Ridge, the seamount chain between Saint Helena and São Tomé and Príncipe, offshore Kenya-Tanzania, western Sri Lanka, the Andaman Islands, eastern Borneo including the Coral Triangle, the Ryukyu Islands, Cape Reinga, and two seamount clusters in the central-northern Pacific. Species distribution models show these zones cover 55% of marine species ranges. IUCN Red List data suggest they contain 29% of fish species and 52% of invertebrates and algae. Alarmingly, none of these zones are currently fully protected under IUCN Categories I-II, and only 0.4% is partially protected.
Systematic planning indicates that protecting 50% of the ocean could theoretically cover all major marine biomes and species. Protecting 30% can safeguard 70–90% of biodiversity, far more effective than non-prioritized protection. Protecting the high seas could also reduce the strict protection needed within national EEZs from 58% to just 7%, achieving similar global biodiversity outcomes.
Immediate action is needed to fully protect the 1% consensus zones, banning all fishing and habitat destruction. Effective MPAs should follow IUCN Categories I or II. Over 90% of current MPAs allow fishing, questioning their effectiveness. Countries should use systematic planning research to design ecologically representative networks. Banning high seas fishing is feasible, as it represents only about 4% of global catch, much of which depends on subsidies, and it aligns with UNCLOS objectives. Fully protected areas also provide spillover benefits, boosting surrounding fisheries and high-value recreational species, without evidence of negative impacts.
In conclusion, the success of global marine biodiversity protection depends on the representativeness and quality of the areas protected. Protecting the 1% of ocean identified by independent studies as “consensus zones” is the most cost-effective first step toward the “30 by 30” goal. This approach also lays a strong foundation for marine ecosystem health and sustainable fisheries. Scientific consensus now points the way, and future results will depend on international collaboration and commitment.