Marine protected areas cover around 10% of the world’s oceans on paper, but new research suggests less than 2% may actually be seeing meaningful recovery of marine ecosystems.
The study, based on underwater biodiversity data collected from thousands of shallow coral and rocky reefs around the world, examined fish populations inside and outside marine protected areas. Researchers used fish biomass the total weight of fish on a reef as an indicator of whether ecosystems were genuinely recovering.
Their findings challenge the assumption that an ocean area labelled “protected” is necessarily delivering effective conservation. The researchers estimate that less than 2% of the global ocean lies within protected areas where marine ecosystems are actually recovering. Even this figure is considered optimistic because it assumes fishing restrictions are being followed.
Marine protected areas have expanded rapidly over the past three decades as governments attempt to tackle overfishing, marine heatwaves, biodiversity loss and other pressures. Under the Kunming-Montreal Global Biodiversity Framework adopted in 2022, 196 countries committed to protecting at least 30% of the world’s land and oceans by 2030, a goal widely known as “30 by 30”.
While roughly 10% of the ocean is currently designated as protected, researchers say the figure does not reveal what is happening beneath the surface.
Fishing remains one of the biggest obstacles to effective protection. Even relatively low levels of fishing can prevent marine communities from fully recovering, particularly where populations of large fish and other vulnerable species have already declined.
The researchers stressed that marine protected areas can work when restrictions are properly enforced. Studies have shown that well managed protected areas can restore fish and shark populations and provide lasting benefits to marine ecosystems.
However, weak enforcement and limited compliance can undermine those gains. The study therefore calls for stronger monitoring and enforcement of fishing regulations, along with greater involvement of coastal communities and other stakeholders in marine stewardship.
Researchers also argue that conservation efforts need much better underwater monitoring. Measuring the number of protected square kilometres or assessing the rules governing an area is not enough to determine whether marine life is actually recovering.
Regular surveys of fish and other marine species both inside and outside protected areas could provide a clearer picture of conservation progress.
The findings suggest that meeting the 30 by 30 target will require more than expanding protected areas on maps. Ensuring that those areas function effectively and that marine ecosystems show measurable recovery will be crucial if global ocean conservation commitments are to translate into real protection beneath the surface.