Australia Passes Legislation to Ratify the High Seas Biodiversity Treaty

Overview

On 31 March 2026, the Australian Federal Parliament passed enabling legislation to ratify the High Seas Biodiversity Treaty, formally known as the 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, commonly abbreviated as the BBNJ Agreement. The treaty entered into force on 17 January 2026, meaning Australia’s domestic legislation has been enacted after the international framework was already legally operative. Australia was among the first nations to sign the treaty in 2023, and the passage of this legislation positions it within a small cohort of countries that have completed the full domestic ratification process. More than 80 countries have now ratified the agreement.

The practical significance of this development cannot be overstated. Approximately 60 per cent of the global ocean sits outside any individual nation’s maritime boundaries or exclusive economic zones, and prior to this framework, less than 1 per cent of that vast area held any form of formal protection or structured environmental oversight. Commercial and industrial activities in the high seas have historically operated in a regulatory vacuum, with no binding international mechanism requiring proponents to assess or mitigate ecological impacts. The BBNJ Agreement fundamentally changes that position by establishing a comprehensive legal architecture covering Environmental Impact Assessments, marine protected areas, marine genetic resources, and capacity building for developing nations.

For marine ecologists, offshore environmental consultants, maritime lawyers, and the developers and operators they advise, this represents a material shift in the compliance landscape. Activities including deep-sea mining, offshore energy infrastructure, subsea telecommunications cable installation, and certain commercial shipping operations conducted beyond national jurisdictions will now be subject to binding international environmental obligations. Australian professionals active in these sectors need to understand the treaty’s mechanisms in detail and begin integrating its requirements into project planning and risk assessment processes without delay.

Key details of the BBNJ Agreement and its core mechanisms

The BBNJ Agreement is structured around four primary pillars: the fair and equitable sharing of benefits arising from marine genetic resources found in areas beyond national jurisdiction; area-based management tools including the designation of highly protected marine areas on the high seas; Environmental Impact Assessment requirements for activities that may cause substantial pollution or significant and harmful changes to the marine environment; and capacity building and marine technology transfer to support developing nations in implementing the framework. Each of these pillars has direct implications for how offshore projects are planned, assessed, and approved.

The Environmental Impact Assessment provisions are the most immediately relevant to practitioners advising on offshore commercial activities. Under the treaty, any activity conducted in areas beyond national jurisdiction that may cause substantial pollution of the marine environment or significant and harmful changes to it will require a formal EIA before the activity can proceed. This obligation applies regardless of the flag state of the proponent vessel or the nationality of the project developer. The EIA must assess potential impacts on marine biological diversity, marine ecosystems, and the broader marine environment. Critically, the standard is one of prevention and precaution: proponents must demonstrate that proposed activities will not cause significant adverse impacts, rather than simply disclosing that impacts may occur. This places a considerable burden of proof on project proponents and their environmental consultants to establish defensible, comprehensive ecological baselines in areas where empirical data is often extremely scarce.

Establishing baseline ecological data in deep-water high-seas environments presents methodological challenges that are qualitatively different from those encountered in coastal or inshore assessments. Water depths across much of the high seas range from 2,000 metres to more than 6,000 metres, with the abyssal plain covering vast tracts of ocean floor that remain poorly characterised biologically. Biological sampling in these environments requires specialised remotely operated vehicles, deep-water acoustic survey equipment, and sediment coring programmes, all of which involve substantial mobilisation costs and extended survey timeframes. The treaty does not prescribe a specific EIA methodology, but the expectation that assessments be scientifically rigorous and internationally peer-reviewed means that practitioners will need to draw on the best available deep-sea ecological science and emerging international guidance as it is developed by the treaty’s governing bodies.

The area-based management tools provisions of the agreement provide the legal mechanism for the international community to designate highly protected marine areas in international waters. This is a historic development: previously, no binding legal pathway existed to establish marine protected areas beyond national jurisdiction. These new designations will directly support the global 30×30 target, which commits nations to protecting 30 per cent of the world’s oceans by 2030. Spatial planning in high-seas zones will need to account for these designations in project routing and site selection, and consultants advising on transnational infrastructure will need to integrate up-to-date information on proposed and confirmed protected area boundaries into their feasibility assessments.

Australian context: how the BBNJ Agreement intersects with existing domestic frameworks

References and related sources

• Primary source: www.foreignminister.gov.au
• EPBC Act

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This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.

Published: 06 Apr 2026

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