Things to know about the High Seas Treaty as it takes effect

The world’s first legally binding agreement to protect marine life in international waters came into effect on Saturday, marking a historic milestone for ocean conservation after nearly two decades of negotiations.

The High Seas Treaty now governs almost half the planet’s surface – the vast ocean areas that lie beyond any country’s territorial control. These waters face mounting threats from destructive fishing practices, shipping, plastic pollution, overfishing, and potential deep sea mining, all exacerbated by climate change. The ocean’s role in absorbing carbon dioxide and producing oxygen makes its health vital for addressing the global climate crisis.

The treaty officially entered into force 120 days after reaching the threshold of ratification by 60 countries in September. As of Friday, 83 nations had ratified it, including recent additions of major maritime powers China and Japan.

One of the treaty’s most significant achievements is creating the first framework for establishing Marine Protected Areas on the high seas, which make up roughly two-thirds of the world’s oceans. Currently, only about 1% of these international waters have any form of protection.

“This treaty represents a fundamental shift in how we approach ocean governance,” said Rebecca Hubbard, director of the High Seas Alliance. “For the first time, we have a legal mechanism to protect biodiversity in areas that have been essentially unregulated for centuries.”

Starting immediately, countries that have ratified the treaty must begin collaborative efforts on ocean science and technology while helping developing nations build capacity to participate in ocean governance. Companies planning activities that could harm marine ecosystems must conduct environmental impact assessments that meet the treaty’s standards. Additionally, those conducting research on marine organisms with commercial potential, such as for pharmaceuticals, must notify other countries and share their findings.

Perhaps most significantly, ratifying countries must now advocate for the treaty’s conservation goals when participating in other international bodies that regulate ocean activities, including regional fisheries organizations, the International Maritime Organization, and the International Seabed Authority.

While key institutions like the treaty’s secretariat and scientific advisory body are still being developed, countries can begin preparing proposals for Marine Protected Areas immediately. Conservation groups have already identified several priority sites, including the Emperor Seamounts in the North Pacific, the Sargasso Sea in the Atlantic, and the Salas y Gomez and Nazca Ridges off South America.

Environmental advocates warn that governments must move quickly to achieve the global goal of protecting 30% of the world’s oceans by 2030 – a target scientists consider critical for ocean health. Given that the high seas comprise such a vast portion of the global ocean, their protection is essential to reaching this objective.

“The marine protected areas under the treaty will only be as strong as the governments make them,” said Megan Randles, global political lead for Greenpeace’s Ocean Campaign. “We can’t trust big fishing industry players to simply stop fishing in these critical ecosystems. We need governments to use the treaty to force their hands.”

How these protected areas will be monitored and enforced remains undecided. Countries are exploring various options, from satellite technology to coordinated multinational patrols to enlisting other UN agencies for oversight assistance. These operational details will be developed as the first protected areas take shape.

Within a year, the treaty’s first Conference of Parties will convene to decide key operational aspects, from budgets to committee structures. Countries have been working through many of these questions during preparatory meetings, with a final planning session scheduled for late March. The earliest any Marine Protected Areas could win approval would be at the second Conference of Parties, since the scientific body that will review proposals has yet to be established.

Notably absent from the list of ratifying countries is the United States, which has signed but not ratified the treaty. This means the U.S. can participate as an observer but won’t have voting rights. Under international law, signatory countries are expected to comply with treaty objectives even before ratification.

“The High Seas Treaty has incredibly broad and strong political support from across all regions of the world,” Hubbard noted. “While it’s disappointing that the U.S. hasn’t yet ratified, it doesn’t undermine its momentum and the support it has already garnered.”

The treaty’s entry into force comes at a critical time for ocean health. Marine ecosystems worldwide face unprecedented pressures from climate change, with rising water temperatures, acidification, and deoxygenation threatening countless species. Commercial fishing fleets venture ever farther into previously untouched waters, while plastic pollution has reached even the deepest ocean trenches.

Conservation advocates emphasize that political support must now translate into rapid implementation to protect vital marine ecosystems before irreversible damage occurs.

“The treaty is a sign that in a divided world, protecting nature and our global commons can still triumph over political rivalries,” Randles said. “The ocean connects us all.”