Earlier this year, ocean conservation advocates celebrated what seemed like a major global milestone: international reports confirmed that 10 percent of the Earth’s oceans had been officially designated as marine protected areas. On paper, this meant that world leaders had successfully implemented varying degrees of fishing restrictions, regulations, and oversight across a tenth of the global ocean’s surface area in an attempt to reduce anthropogenic pressures on delicate marine ecosystems and allow them to thrive.
This achievement was widely heralded as tangible progress toward a prominent United Nations goal known as 30×30, which aims to conserve 30 percent of the planet’s land and ocean area by the end of the decade. Environmental campaigns, philanthropic organizations, and governments pointed to the expanding square mileage of protected waters as definitive proof of a turning tide in global conservation efforts, pouring hundreds of millions of dollars into establishing new designations.
However, new research published in the journal PNAS suggests that the widely celebrated 10 percent figure is deeply misleading. The study found that only a small fraction of implemented marine protected areas, commonly known as MPAs, are actually making a substantial, measurable difference for the aquatic ecosystems they are legally supposed to safeguard. This shortfall is driven largely by low compliance with fishing restrictions, inadequate monitoring, and weak management. 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 fish populations are rebounding.
The research raises profound questions about the broader 30×30 approach, which has historically prioritized a protected area’s square mileage and sheer geographic footprint over its actual ecological efficacy. The study’s authors argue that the international conservation community desperately needs to think beyond simple area-based conservation metrics and begin evaluating what is truly 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 new research paper.
The modern conservation world’s intense focus on area-based targets emerged in the early 2000s. At a landmark United Nations meeting in 2002, world leaders agreed in principle to establish comprehensive networks of MPAs, though they initially stopped short of setting a rigid target for how much of the global ocean those networks should cover. Two years later, at a high-level meeting of the Convention on Biological Diversity—the U.N.’s principal treaty dedicated to protecting life on Earth—participating countries introduced a quantitative goal. They formally agreed to conserve at least 10 percent of each of the world’s distinct ecological regions, largely through the establishment of protected zones.
A subsequent meeting in 2010 updated that target to protect 10 percent of the oceans specifically by the year 2020. When that deadline arrived and the goal was ultimately missed, the 30×30 initiative emerged as its successor, integrated as a cornerstone of a broader international agreement known as the Global Biodiversity Framework.
Angelo Villagomez, a senior fellow focusing on Indigenous-led conservation policy for the Center for American Progress, explained that the reason nations have so readily rallied behind a quantitative, area-based target is fundamentally straightforward. "It is easy to measure and communicate," he noted.
Scientists and policymakers understood early on that this political simplicity was critical for securing broad international support for conservation initiatives. At the time, that political necessity frequently outweighed growing concerns that governments would designate MPAs in remote, out-of-sight areas that did not possess high levels of biodiversity to begin with. Critics warned that nations might simply create "paper parks"—vast regions drawn on maps that lacked any real-world enforcement or implemented conservation measures.
Fast-forward to the present day, and it is worth asking whether the hundreds of millions of dollars being poured into MPAs annually are actually helping marine life. Are these designations genuinely increasing fish populations and structural habitat health, or are they merely increasing the percentage of ocean area covered by impressive-sounding political declarations?
To answer this critical question, Clausius and her research team developed a pair of sophisticated models. The first model utilized real-world observational data gathered from protected and unprotected shallow coral reefs to estimate the direct effects of several hundred distinct protected areas on local marine biomass. The researchers then linked those observed ecological effects to four measurable characteristics of the locations: their official level of protection, the rate of local compliance with fishing regulations, their total size, and their age since establishment. Finally, they used those established relationships to estimate the conservation effects for the vast majority of the world’s MPAs that completely lack on-the-ground observational data.
The results of the modeling were sobering. They suggested that only one-fifth of the ocean area currently designated as an MPA is actually "ecologically effective." The researchers defined this effectiveness as contributing to a measurable doubling in local fish biomass.
This widespread underperformance is partly because so few designated areas actually offer full, no-take protection from fishing, which marine scientists maintain is necessary to deliver the absolute best conservation benefits. But it is also driven heavily by poor management and widespread non-compliance in areas that do have rules on the books.
Indeed, Clausius pointed out that violations of fishing restrictions are so pervasive in certain regions that it is not uncommon to witness compliance officers themselves breaking the rules. She recounted instances where authorities visit protected areas and then cast fishing lines off the back of their own patrol boats. "They know they can get the big fish there," she said, highlighting the human element undermining well-intentioned policy.
The findings from Clausius and her team add considerable scientific weight to longstanding criticisms regarding the overall effectiveness and equity of the 30×30 framework, particularly its disproportionate emphasis on the sheer size of MPAs over their quality.
Callum Roberts, a marine conservation professor at the University of Exeter in the United Kingdom, offered two alternative metrics that the global community should focus on instead: each area’s specific level of legal protection from fishing and other commercial activities, and its "stage of establishment," which ranges from merely proposed to actively managed on the water.
Another researcher, Bruce Mann with the South African Association for Marine Biological Research, previously suggested a conceptual framework known as NEOLI. This framework outlines five key characteristics of MPAs—no-take, enforced, old, large, and isolated—as much more accurate indicators of whether a marine protected area will succeed.
Of course, experts acknowledge that even these characteristics are still ultimately proxies for what conservationists truly want to measure: overarching ecosystem health. Yet, coming up with a single, universal metric for ecosystem health remains extraordinarily difficult, according to Clausius, because marine ecosystems differ so dramatically across the globe and face entirely different localized threats. For example, measuring fish biomass might be highly appropriate for nearshore tropical areas struggling with intense overfishing, but it would not be nearly as useful a metric for evaluating an MPA primarily intended to protect fragile benthic habitats from the impacts of deep-sea mining.
Despite these criticisms, Villagomez defended the 30×30 initiative as a uniquely useful 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."
However, Villagomez agreed with other experts who argue that the relentless focus on 30×30 has fostered a problematic obsession with total geographic size. He has been working on developing alternative approaches for the United States that would prioritize beloved ecological areas and coastal habitats close to population centers in each of the 35 coastal and Great Lakes states and territories. This approach stands in sharp contrast to the current trend of establishing massive, distant, and isolated protected areas in remote oceanic basins that see little human interaction.
George Branch, an emeritus biology professor at the University of Cape Town in South Africa, went a step further, describing the overarching 30×30 target as overambitious. He argued that at this stage in the global climate and biodiversity crises, it may be far more productive to improve the management and ecological effectiveness of existing marine protected areas rather than racing to add new ones that lack enforcement.
Another fundamental reason to look beyond the narrow confines of the 30×30 framework is the urgent necessity for better, more comprehensive ocean management everywhere, not just inside designated boundaries.
"We can’t just do whatever we want in the other 70 percent of the oceans," Clausius told Grist. In vast marine regions where total, permanent fishing bans are not socially or economically appropriate—whether for cultural, subsistence, or commercial fishing reasons—there remain vital, proven ways to protect ecosystems from pollution and overexploitation. These include establishing science-based catch limits, protecting spawning grounds, and strictly regulating coastal development.
"It needs to be a global oceans picture," Clausius added, emphasizing that the health of the seas depends on holistic stewardship rather than isolated lines drawn on a map.