Earlier this year, ocean conservation advocates celebrated what appeared to be a major milestone in global environmental policy: data showed that 10 percent of the Earth’s oceans had been officially designated as marine protected areas. In theory, this achievement meant that world leaders had successfully implemented varying degrees of fishing restrictions, regulations, and conservation mandates across a tenth of the global ocean’s surface area. The primary objective of these designations is to reduce industrial and commercial pressures on fragile marine ecosystems, allowing them to recover, heal, and ultimately thrive.
Furthermore, reaching this 10 percent mark was widely heralded as tangible progress toward an ambitious United Nations initiative known as 30×30. This landmark global target aims to formally conserve 30 percent of the planet’s land and ocean area by the year 2030, a goal intended to halt biodiversity loss and build climate resilience across terrestrial and aquatic biomes.
However, new research published in the journal PNAS suggests that the celebratory 10 percent figure is profoundly misleading. The study revealed that only a tiny fraction of implemented marine protected areas, commonly referred to as MPAs, are actually making a substantial, measurable difference for the ecosystems they were legally established to protect. The primary driver behind this shortfall is a widespread lack of compliance with established fishing restrictions and management rules. Conservatively, the study’s authors estimated that a mere 2 percent of the world’s oceans are genuinely covered by MPAs where ecosystems are actively recovering and functioning as intended.
This newly released research raises critical questions about the broader 30×30 approach, which has historically prioritized a protected area’s raw square mileage over its ecological efficacy. The study’s authors argue that the international conservation community urgently needs to look beyond simple area-based metrics and begin evaluating what is actually happening to aquatic life beneath the surface.
“There’s this large disconnect between what we think is effectively protected globally, which is now 10 percent of the oceans, and what’s actually effectively conserving marine ecosystems underwater,” said Ella Clausius, a postdoctoral research fellow at the University of Tasmania and the lead author of the paper.
The conservation world’s heavy reliance on area-based targets emerged during the early 2000s. At a United Nations meeting in 2002, world leaders initially agreed to establish interconnected networks of MPAs, though they notably refrained from setting a hard numerical target for how much ocean territory those networks should encompass. Just two years later, at a meeting of the Convention on Biological Diversity—the U.N.’s principal treaty dedicated to preserving life on Earth—participating countries introduced a quantitative goal. They formally agreed to conserve “at least 10 percent of each of the world’s ecological regions,” relying heavily on the creation of protected areas to meet the target.
A subsequent international meeting in 2010 updated the goal, explicitly calling for the protection of 10 percent of the global oceans specifically by the year 2020. When that deadline arrived and the target was missed, the 30×30 initiative emerged as its natural successor, eventually becoming a cornerstone of a broader international agreement known as the Global Biodiversity Framework.
According to Angelo Villagomez, a senior fellow focusing on Indigenous-led conservation policy for the Center for American Progress, the underlying reason why nations have overwhelmingly rallied behind a quantitative, area-based target is remarkably straightforward. “It is easy to measure and communicate,” Villagomez explained.
For political leaders and international diplomats, scientists understood that this communicative simplicity was critical for securing widespread political support for conservation initiatives. At the time, that political pragmatism largely outweighed mounting concerns that nations would simply designate MPAs in remote, deep-sea regions that lacked significant biodiversity to begin with, or that governments would establish “paper parks”—areas that carry protective legal designations on paper but lack any active management, enforcement, or conservation measures on the water.
Fast-forward to the present day, however, and it is entirely reasonable to ask whether the hundreds of millions of dollars being poured into marine protected areas annually are genuinely helping marine life. Are these designations actually increasing fish populations and rebuilding depleted stocks, or are they merely driving up the percentage of ocean area covered by lines drawn on a map?
To find a definitive answer to this complex question, Clausius and her research team constructed a pair of sophisticated models. The first model utilized real-world observational data gathered from both protected and unprotected shallow reefs to estimate the direct effects of several hundred established protected areas on overall marine biomass. The researchers then linked those observed ecological effects to four measurable characteristics of each location: its strictness of protection, its actual level of compliance with fishing regulations, its total geographic size, and its age since establishment. Finally, they applied these established relationships to estimate conservation outcomes for the majority of the world’s MPAs that completely lack observational monitoring data.
The results of the modeling were sobering. They suggested that only about one-fifth of the ocean area currently designated as MPAs is genuinely “ecologically effective,” a standard the researchers defined as contributing to a measurable doubling in fish biomass. This widespread underperformance occurs partly because so few designated areas actually offer full, no-take protection from fishing—a level of restriction that scientists insist is strictly necessary to deliver the best possible conservation benefits. Furthermore, the shortfall is driven significantly by poor management and widespread non-compliance in areas where rules do exist.
In fact, Clausius noted that violations of fishing restrictions are so pervasive across global MPAs that it is not uncommon to witness compliance officers themselves breaking the rules. She recounted instances where local authorities charged with enforcing regulations visit protected areas only to cast fishing lines off the back of their own patrol boats. “They know they can get the big fish there,” she said.
The findings published by Clausius and her team lend considerable scientific weight to longstanding criticisms regarding the overall effectiveness and equity of the 30×30 framework, particularly its persistent emphasis on the physical size of MPAs over their operational quality.
Callum Roberts, a professor of marine conservation at the University of Exeter in the United Kingdom, offered two alternative metrics that policymakers should focus on instead of raw acreage: each area’s specific level of protection from fishing and other commercial activities, and its “stage of establishment,” which ranges from merely proposed to actively and rigorously managed.
Meanwhile, another researcher, Bruce Mann with the South African Association for Marine Biological Research, has long championed a framework known as NEOLI. This acronym describes five distinct characteristics of MPAs—no-take, enforced, old, large, and isolated—as more accurate and reliable indicators of whether a protected area will successfully fulfill its conservation mandate.
Of course, researchers readily acknowledge that even these characteristics remain proxies for what conservationists ultimately want to measure: the holistic health of the marine ecosystem. Yet, finding a universal metric for ecosystem health is exceptionally difficult, according to Clausius, because aquatic ecosystems differ dramatically across the globe and face entirely different localized threats. For instance, tracking fish biomass might be an appropriate and effective metric for coastal areas struggling with chronic overfishing, but it would not serve as a useful metric for evaluating MPAs whose primary conservation purpose is to protect delicate seafloor habitats from the impacts of deep-sea mining.
Despite these scientific shortcomings, Villagomez defended the 30×30 initiative as an exceptionally valuable political pledge. “It has elevated environmental protections to the highest levels of government around the world,” he said. “It’s unlocked millions of dollars of funding. Leaders of countries all around the world agree that we need more ocean conservation, better conservation, and that we need it faster than ever.”
Even so, Villagomez agreed with fellow experts who argue that the 30×30 movement has fostered a problematic obsession with geographic size. To counter this, he has been helping develop alternative policy approaches for the United States. One such proposal would prioritize “beloved ecological areas and coastal habitats” across all 35 coastal and Great Lakes states and territories—focusing on regions that sit close to where human populations actually live, work, and recreate, rather than relying on what he describes as large, distant, and ecologically isolated protected areas far out at sea.
George Branch, an emeritus professor of biology at the University of Cape Town in South Africa, echoed these cautionary sentiments, calling the 30×30 target “overambitious.” He suggested that at this advanced stage in the global environmental crisis, it may prove far more productive to focus on drastically improving the management and ecological effectiveness of existing MPAs rather than rushing to designate new ones on paper alone.
For Clausius and her colleagues, the new data underscores an even broader truth: humanity cannot afford to treat marine conservation as a piecemeal exercise limited strictly to designated zones. True global ocean health requires a fundamental shift in how we manage waters everywhere, not just inside protected boundaries.
“We can’t just do whatever we want in the other 70 percent of the oceans,” Clausius said.
Even in vast marine regions where total commercial fishing bans are entirely inappropriate—whether for cultural, subsistence, or economic reasons—there remain numerous viable pathways to shield vulnerable marine ecosystems from pollution and severe overexploitation. These include implementing rigorous, science-based catch limits, strictly regulating coastal development, and actively managing human interactions with the sea.
“It needs to be a global oceans picture,” Clausius added.