Changing Tides

The first international agreement to protect the world’s oceans aims to create “international parks” in the high seas.

By Jackie Gu, Reuters


After almost 20 years of negotiations, United Nations member countries have agreed upon an international treaty to protect oceans of the world that lie outside national borders.

These waters, known as “high seas,” occupy nearly two-thirds of the world’s oceans. Because they are considered international waters, they lie outside the jurisdiction of any state and have until now never been legally protected, meaning that the marine life in these areas has been under threat from a free-for-all of unregulated exploitation – including overfishing, pollution from ships and human-induced climate change.

Oceans make up over 70% of the Earth’s surface.

Exclusive economic zones (EEZs) extend 200 nautical miles (370km) from the coasts of a nation’s land.

In these zones, the coastal nation has jurisdiction over living and nonliving resources in the water and on ocean floors.

Ocean waters beyond EEZs are known as the high seas. They belong to no nation, and have thus far never been legally protected.

The treaty, whose text was finalised on March 4, lays the groundwork for marine protections over previously unregulated waters. Known as the Biodiversity Beyond National Jurisdiction treaty (BBNJ), its primary aim is to protect biodiversity by establishing large-scale marine protected areas and regulating marine research for scientific and commercial development.

It comes at a crucial time for conservation efforts: In 2022, UN countries signed a landmark agreement that aims to protect at least 30% of the planet’s land and water by 2030–the “30×30” goal. But according to the Marine Conservation Institute, only a little under 3% is fully or highly protected.

The high seas represent 95% of the world’s total habitat by volume, but the nautical world remains largely unexplored. Though estimates vary, one study from 2011 suggests we have classified only about 9% of ocean species. More than 80% of the oceans have never been mapped, observed or explored.

The International Union for Conservation of Nature’s Red List, which assesses species for global extinction risk status, has evaluated only 17,903 of the estimated 240,000 marine species known to scientists – but of these, nearly 9% are at risk of extinction. Scientists predict marine extinction risk will skyrocket in the next few years because of rapidly developing infrastructure in the oceans.

Compared to land animals, marine extinction risk has remained relatively low. According to a paper in the journal Science, there have been 514 animal extinctions on land during the past 500 years, compared with only 15 ocean extinctions in the same period. Land extinctions accelerated greatly during and after the Industrial Revolution, as humans inflicted carnage on forests and prairies at a breakneck pace.

Now, though, humans have begun building infrastructure in the oceans – such as agriculture, mining and power plants – presaging an almost certain uptick in extinction risk for marine species.

A bird’s-eye image of the ocean shows rows of white circular fishing nets against the teal ocean. A worker is collecting the nets.
An ocean farming facility is being towed by a small white tugboat at a port. The facility is a large structure that looks like a cage; its frame is painted yellow.
A close-up image shows a bag full of the sand of tin ore; it looks like dark sand. There is a hand holding the bag open and another hand holding a palmful of the tin ore.


A worker collects fishing nets at an aquaculture company in Xuzhou, China. REUTERS/Stringer

An offshore ocean farming facility to be delivered to Norway is towed by a tugboat at a port in Qingdao, China . REUTERS/Stringer

Hendra, 51, a tin miner, shows the sand of tin ore on a pontoon off the coast of Toboali, on the southern shores of the island of Bangka, Indonesia, April 29, 2021. “On land, our income is diminishing. There are no more reserves,” said Hendra, who shifted to work in offshore tin mining about a year ago after a decade in the industry. “In the ocean, there are far more reserves.” REUTERS/Willy Kurniawan

“We’re effectively seeing an industrial revolution in the ocean,” said Douglas MacCauley, an ecologist at the University of California Santa Barbara and co-author of the Science paper. “The land’s past is becoming the ocean’s present.”

Between the “explosion of the blue economy” and the increasing effects of climate change, he said, ocean life faces existential threat.

Data corroborates these findings: the Red List Index, which evaluates trends in overall extinction risk for species, is used as a metric for tracking biodiversity loss. For the past 30 years, marine species have been rapidly moving towards increased extinction risk.

Marine species’ survival odds have tanked the fastest

The Red List Index of species survival for animals in different habitats

The chart below shows how the Red List Index (RLI) for animals of migratory, freshwater, terrestrial, marine, and forest species has changed from 1993 to 2020. The RLI for marine species has dropped the fastest.

Note: Only includes species from mammals, birds, amphibians, cycads, and reef-forming corals

Source: IUCN Red List

Where should the marine protected areas go?

The treaty’s objective to establish large-scale marine protected areas is a significant step towards the global 30×30 conservation goal. The National Resources Defense Council describes these marine protected areas as “the ocean’s equivalent of a Grand Canyon or Yellowstone National Park,” where protections exist to limit human activity and allow ocean life to recover.

Management of these areas may encompass a range of protections: the strictest zones ban all human entry, whereas others may allow some fishing and snorkelling. A 2018 study found that effective MPAs contain two and a half times the total biomass of fish than fished areas.

A large silver fish swims among a school of hundreds of fusilier fishes. The fusiliers are vibrantly colored, blue with a horizontal yellow stripe.
A trevally chases fusiliers near Lankayan Island located in the Sulu-Sulawesi Marine Ecoregion, in the Malaysia’s state of Sabah on the Borneo Island, on January 9, 2004. The Sulu-Sulawesi Marine Ecoregion bordered by Indonesia, Malaysia and Philippine, is the world’s richest area for marine life, home of the 45 million inhabitants. – REUTERS

As for where to place these protected regions, a team of researchers led by McCauley conducted a data-driven analysis to identify biodiversity hotspots in the high seas. Life in the oceans, like on land, isn’t homogeneously distributed. The team published a paper in 2020 spotlighting specific marine regions to prioritise for protection, basing their analysis on a number of conservation features, such as species richness, extinction risk and habitat diversity.

The research unfolded adjacent to the treaty negotiation process. McCauley, along with several of the other researchers, travelled to the UN several times to present their findings.

“A sentiment we often encountered was that there’s not much in terms of biodiversity out there in the high seas,” he said. “People thought, why create these parks if we’re just throwing darts at a map? But the idea that it’s a big blue empty desert isn’t true.”

The Mascarene Plateau is home to one of the few shallow water coral reef ecosystems in the high seas and the largest continguous seagrass beds in the world. The pygmy blue whale uses the area as a breeding and feeding ground.

Because fishing in the Salas y Gomez and Nazca Ridges has so far been limited, these deep-sea mountains contain some of the world’s highest levels of endemic marine diversity and could be important for the survival of yet-undiscovered species.

Lord Howe Rise and the South Tasman Sea are some of the most biodiverse waters on the high seas, home to humpback whales and a high number of threatened species.

These shaded areas are the result of the analysis conducted by researchers at University of California Santa Barbara. They highlight the regions that would protect at least 30% of all conservation features and should thus be considered high priority for MPA establishment.

MPAs that already exist mostly occupy exclusive economic zones and only make up about 3% of the high seas.

Protecting critical areas of the ocean could additionally help build global resilience to climate change. Almost half of the world’s oxygen comes from phytoplankton in the oceans. The high seas absorb carbon dioxide from the atmosphere–estimates land at around 30% of all carbon emissions–blunting the impact of climate change on land and sea alike.

Though it’s expected to take another several years for the treaty to be carried out in concrete policy, Nichola Clark, an officer at the Pew Charitable Trusts and co-author of the research paper, said she is hopeful that the analytical approach to the protected areas was helpful for “impressing the urgency of the situation and the necessary scale of the solution upon policymakers.”

A large, spotted whale shark swimming next to volunteer divers that are removing a fishing net from the water.
A whale shark swims next to volunteer divers after they removed an abandoned fishing net that was covering a coral reef in a protected area of Ko Losin, Thailand – REUTERS/Jorge Silva

“This ability to set up international parks on the high seas, by all people and for all people, is one of the most exciting outcomes of the treaty for me,” MacCauley said. “And they will be absolutely as special as underwater Serengetis or Yellowstones.”

The long road to treaty negotiations

The treaty took nearly two decades to come to fruition, though official meeting sessions took place over the span of only five years. They were further delayed over the past two years because of the COVID-19 pandemic. Negotiations were saddled with disagreements over funding and fishing rights.

The legally binding pact to conserve and ensure sustainable use of ocean biodiversity was finally agreed upon on March 5, after five rounds of negotiations.



UN Biodiversity Beyond National Jurisdiction (BBNJ) group is established to study marine conservation issues.


UN General Assembly (UNGA) adopts Resolution 61/105 to prohibit fishing on species for which population size has not yet been determined and promote sustainable bottom fishing in areas beyond national jurisdiction.


BBNJ agrees upon a breakthrough “package” of issues to address concerning the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction.


BBNJ adopts UNGA Res. 69/292, which establishes a Preparatory Committee to develop a legally binding instrument for the issues to address.


Preparatory Committee recommends convening an Intergovernmental Conference (IGC).


IGC convenes its first session.


IGC convenes its fifth session from February 20-March 3 in New York City, in which the High Seas Treaty was formally signed by all member states of the UN.

The timeline below shows the timeline of UN events leading up to the treaty being signed. It starts in 2004, when the UN Biodiversity Beyond National Jurisdiction (BBNJ) group was first established to study marine conservation issues. It ends in 2023, when the BBNJ Treaty was formally signed by all member nations of the UN.

Sweden, which was involved in the negotiations as the holder of the EU’s rotating presidency, said the agreement was the “most important international environmental deal” since the 2015 Paris Agreement on tackling climate change.

Economic interests were a major sticking point throughout the negotiations, with developing countries calling for a greater share of the spoils from the “blue economy”, including the transfer of technology.

An agreement to share the benefits of “marine genetic resources” used in industries such as biotechnology also remained an area of contention until the end.

Countries will have to meet again to formally adopt the treaty.

Haphazard authority on ocean resources

A fragmented patchwork of international bodies and treaties manages ocean resources. Each body has a different scope, and few mechanisms exist to coordinate among them, resulting in a leaky net of regulations where vast swathes of the ocean fall through the gaps.

2016 Pew study on mapping governance in the high seas showed 19 governing bodies with a high seas mandate. Of these, the majority are limited in scope to management of fisheries. Only six have a mandate that focuses primarily on marine conservation.

The study noted that “none has a comprehensive cross-sectoral mandate with regulatory authority and a focus on conservation in areas beyond national jurisdiction.”

The lack of regulation has led to unfettered exploitation of marine areas rich in biodiversity – such as “undersea mountains that are rimmed with 4,000-year-old gold coral and rainbow fish you can’t find anywhere else on the planet,” McCauley said. “There’s been no way to prevent those species from getting decimated.”

There is still a long way to go before the treaty can take effect. Member nations need to meet again to sign and ratify the treaty, which will likely take years. Only after that can governments begin to formally propose where to establish the marine protected areas, each of which will be individually voted on for approval.

“The treaty is a really important milestone,” McCauley said. “But the hardest work is ahead.”


Data as of March 2023


University of California Santa Barbara analysis; Pew Charitable Trusts;; International Union for Conservation of Nature; Marine Conservation Institute; Protected Planet

Edited by

Anand Kakatam and Gerry Doyle


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