BBNJ Agreement: Protecting marine biodiversity in the High Seas

The BBNJ Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction (BBNJ), is also known as the High Seas Treaty or Ocean Biodiversity Treaty. Adopted on 19 June 2023, the Agreement/Treaty protects the deep sea through conservation measures like marine protected areas and promotes equity through rules about sharing the benefits from research on marine genetic resources (MGR) of areas beyond national jurisdiction (ABNJ). MGR are the building blocks of biodiversity and unlocking their secrets is crucial for the health of the planet and its people. The Treaty is a blueprint with new rules for two-thirds of the world’s oceans, but there are many practical details to be fleshed out by Treaty bodies when it enters into force next month in January 2026 and regulates marine biodiversity beyond borders of national jurisdiction.

Although the high seas are teeming with life, from fragile deep-sea corals to iconic whales, fewer than 1.5% of these vast international waters are protected. The BBNJ Agreement is establishing a comprehensive legal framework to create marine protected areas (MPAs), requiring environmental impact assessments (EIAs) for activities that may harm the ocean and its biodiversity, while promoting the fair and equitable sharing of MGRs. But what will this landmark agreement mean for global marine biodiversity conservation?

According to the Biodiversity Finance Network, the real challenge of the Agreement will be turning its provisions into meaningful real-world protection at sea, requiring strong international commitment and coordinated global action. They identify four key steps to ensure its success:

1. Leveraging regional bodies: The Agreement cannot work in a vacuum. Its success hinges on collaboration with existing regional organisations - like the Benguela Current Convention in southern Africa or the OSPAR Commission in the North Atlantic. These bodies possess critical regional knowledge and must become the engines for proposing and managing high seas MPAs, creating a connected network of protected sanctuaries.
2. Building a global science platform: The Agreement’s provisions on EIAs demand robust, accessible baseline science. We need a global effort to share data, fund high-seas research and establish common standards for monitoring. This is not just a task for wealthy nations; a cornerstone of the Agreement is building the capacity of all states to participate meaningfully in this new frontier of marine science.
3. Ensuring equity from the start: The fair sharing of benefits from MGRs is a core pillar of the Agreement. We must establish transparent mechanisms that ensure discoveries in the deep-sea benefit humanity, supporting conservation and sustainable development worldwide. This means prioritising technology transfer and capacity building for developing states, turning a principle on paper into practice.
4. Establishing a robust compliance and monitoring mechanism: A critical success factor will be the creation of a transparent and effective global system for monitoring compliance and reporting on the status of MPAs. This will involve leveraging satellite technology, vessel monitoring systems, and even AI-powered surveillance to track human activity, combat illegal fishing, and ensure that parties are adhering to EIA conditions.

The BBNJ Agreement is a historic achievement, a major step forward for the conservation and sustainable use of marine biodiversity in areas beyond national jurisdiction but implementation will determine whether it succeeds, important work still lies ahead.

With the Agreement set to enter into force on 17 January 2026, this month the Deep-Ocean Stewardship Initiative (DOSI) released a new policy brief - Towards coherence and avoiding undermining: policy recommendations on implementation of the BBNJ Agreement regarding marine genetic resources, with valuable contributions from MARBLES partner Abbe Brown (University of Aberdeen (UNIABDN)). The policy brief was borne from the 'Implementing the New UN BBNJ Ocean Treaty' Workshop in July 2025, which was co-sponsored by UNIABDN, London School of Economics’ Oceans Biodiversity Collective, MARBLES, fellow EU projects BlueRemediomics and HOTBIO, and DOSI. It offers guidance to support the effective implementation of the Agreement, particularly in relation to Instruments, Frameworks, and Bodies (IFBs) as well as MGRs, with a particular focus on approaches consistent with the common heritage of humankind as set out in the Convention, and stewarding for future generations.

MARBLES partner Marcel Jaspars (UNIABDN) and MARBLES Advisory Panel of Policy and Legal Experts (APPLE) member, Arianna Broggiato (EC DG MARE) also contributed to a useful guide on the Agreement for ocean research scientists in Marlow etal. (2025).

A variety of resources have also been developed by the UN’s Division for Ocean Affairs and the Law of The Sea (DOALOS) and are available for those wishing to learn more about the Agreement e.g., factsheets, video, recorded briefings and an e-course. List of countries that have signed or ratified the BBNJ Agreement

Quotes and perspectives have been extracted from this Biodiversity Finance Network article