High Seas Treaty: A New Era for Migratory Species and Ocean Governance

Bonn, 25 September 2025 - The Agreement under the United Nations Convention on the Law of the Sea (UNCLOS) on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction (BBNJ Agreement) has reached the threshold for entry into force. This historic milestone marks the beginning of a new era for the conservation and sustainable use of marine biodiversity in the high seas—an area covering two-thirds of the world’s ocean.

Why It Matters for CMS and Migratory Species

For the Convention on the Conservation of Migratory Species of Wild Animals (CMS), the upcoming entry into force of the BBNJ Agreement opens new avenues to advance the conservation of migratory species across marine ecosystems. The Treaty complements existing multilateral environmental agreements and strengthens the global framework for conservation measures related to species that traverse vast oceanic territories, and their habitats.

“With the imminent entry into force of the BBNJ Agreement, CMS stands ready to contribute its expertise to ensure migratory species are fully considered in the implementation of this historic Treaty. This is a moment of hope and opportunity for the ocean and for all life that depends on it.” 

Amy Fraenkel, CMS Executive Secretary

CMS and the BBNJ Agreement: Stepping Together for Migratory Species

CMS is a legally binding treaty in force since 1983, with provisions that extend beyond national jurisdiction and cover the high seas. In particular, CMS Parties that are Range States of a migratory species listed in CMS Appendix I are prohibited from taking such species.  A Range State includes flag vessels of a State which are engaged outside national jurisdictional limits in taking migratory species. Further, such governments are to address adverse threats, and ensure ecological connectivity for such species.

Migratory species rely on various important habitats for their survival, and need to be able to access such areas. CMS has a long-standing role in the identification and conservation of important habitats for migratory species, including sharks, rays, marine mammals, and turtles. The Convention stands ready to contribute scientific information and detailed maps identifying important areas for conservation, ensuring ecological connectivity across ocean basins.

CMS also provides assessments on key threats such as fisheries-induced mortality, ship strikes, underwater noise, and marine pollution, and has developed comprehensive guidelines to address these threats. This expertise is vital for effective implementation of the provisions under the new high seas treaty on environmental impact assessment.

The BBNJ Agreement is the first legally binding international instrument dedicated to safeguarding marine life in areas beyond national jurisdiction, which comprise two-thirds of the world’s ocean. It provides a framework for:

• Establishing marine protected areas (MPAs) in international waters.
• Conducting environmental impact assessments for activities on the high seas.
• Ensuring equitable access and benefit-sharing of marine genetic resources.
• Supporting capacity building and technology transfer, especially for developing countries.

Key Priorities for Collaboration under BBNJ

CMS’s collaboration with the BBNJ Agreement could focus on two critical areas:

• Implementation of area-based management tools, including marine protected areas (MPAs): Ensuring these areas are well located and form part of a network of habitats to maintain ecological connectivity between populations and life stages.
• Identifying key threats from human activities on the high seas and solutions to mitigate such pressures: Addressing impacts from fisheries, deep-sea mining, habitat destruction, underwater noise, and ship traffic, all of which can significantly affect migratory species in marine environments. 

Recent CMS Mandates and Synergies

At CMS COP14, Parties established new mandates on pressing issues such as habitat connectivity, assessing possible impacts of deep-seabed mineral exploitation activities on migratory species, area-based conservation, bycatch, and vessel strikes. Notably, the COP endorsed the IUCN Important Shark and Ray Areas (ISRAs) concept and called for measures to reduce vessel strikes on marine megafauna. The CMS Secretariat was also tasked to enhance cooperation with the BBNJ process and other relevant bodies, and to report on progress at each COP.

CMS Parties are encouraged to ratify the BBNJ Agreement at their earliest convenience to advance the conservation of migratory species.

Looking Ahead: CMS COP15

The timing of the BBNJ Agreement’s entry into force is especially significant as the international community prepares for the 15th Meeting of the Conference of the Parties to CMS (CMS COP15), to be held in Campo Grande, Brazil, from 23–29 March 2026. COP15 will provide a critical platform for CMS Parties to align their conservation priorities with the new legal landscape shaped by the BBNJ Agreement. Key issues will include amendments to CMS Appendices, new concerted actions, measures to address illegal and unsustainable taking of migratory species, and actions to advance ecological connectivity in marine environments.

CMS keenly follows the next steps of the BBNJ process and is prepared to provide its expertise on matters related to migratory species. The Secretariat looks forward to working with all stakeholders to ensure that the conservation of migratory species remains central to the implementation of the BBNJ Agreement and to the decisions taken at COP15.

List of specialised agreements concluded under CMS with a focus on the conservation aquatic migratory species