1.1 High seas and marine biodiversity
This thesis analyses the obligations of flag States concerning the protection of marine biodiversity in the areas beyond national jurisdiction (‘ABNJ’). The topic is particularly interesting as the obligations are aimed at addressing the complex and evolving role of flag States in managing and safeguarding marine biodiversity in an area that has been largely unregulated and vulnerable to over-exploitation. For the purposes of this thesis, the terminology of the United Nations Convention on the Law of the Sea (‘UNCLOS’)(1)United Nations Convention on the Law of the Sea (adopted 10 December 1982, entered into force 16 November 1994, Montego Bay) 1833 UNTS 3 (UNCLOS) and 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 (‘BBNJ Agreement’)(2)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 (adopted 19 June 2023, entered into force 17 January 2026, New York) (BBNJ Agreement) is followed. References to “State Party” describe States legally bound by UNCLOS. Where the BBNJ Agreement is concerned, the term “Parties” is used in accordance with its text. References to “flag States” refer to State Parties to UNCLOS acting in their capacity as flag States, exercising jurisdiction and control over vessels flying their flag.
Flag States can play a critical role in mitigating impacts on marine biodiversity in ABNJ by ensuring that their vessels adhere to international agreements. Understanding the obligations and responsibilities of flag States is critical, as the flag States and the shipping industry play a central role in enforcing international regulations and ensuring compliance with conservation measures. Shipping activities have a significant impact on marine biodiversity in many ways(3)Casey O’Hara, Melanie Frazier, Benjamin Halpern, ‘At-risk marine biodiversity faces extensive, expanding, and intensifying human impacts’ (02.04.2021) Science, vol. 372, Issue 6537, such as through the introduction of invasive species transported by ballast water, destruction of habitats, pollution caused by oil spills, noise pollution, invasive non-native species, and sewage discharge. Notably, the Arctic Council has highlighted a range of impacts on the high seas in the Arctic, including vessel strikes affecting whales and other marine mammals, and atmospheric emissions from shipping that contribute to climate change and indirectly intensify pressures on marine life(4)Arctic Council, ‘Arctic Marine Shipping Assessment 2009 Report’ ('Protection of the Arctic Marine Environment (‘PAME’), Arctic Council 2009), page 152-153.
UNCLOS defines the high seas as “all parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a State, or in the archipelagic waters of an archipelagic State”(5)Article 86 UNCLOS. In general terms, the high seas comprise ocean areas beyond the limits of national jurisdiction, outside territorial seas and, where established, exclusive economic zones that may extend up to 200 nautical miles from the coastal baseline; as a whole, the high seas account for approximately 95 per cent of the ocean’s volume and nearly half of the Earth’s surface(6)Directorate-General for Maritime Affairs and Fisheries, ‘A win for the ocean: High Seas Treaty signed at United Nations’ (20.09.2023), Awin for the ocean: High Seas Treaty signed at United Nations - European Commission (europa.eu) accessed 14.05.2026. ABNJ encompass both the high seas and the seabed beyond national jurisdiction and are referred to as a part of the global commons, requiring collective management and protection for the benefit of all(7)United Nations Environment Programme, ‘Making Peace With Nature: A Scientific Blueprint to Tackle the Climate, Biodiversity, and Pollution Emergencies’ (2021) https://www.unep.org/resources/making-peace-nature accessed 14.05.2026.
The significance of the high seas is further reflected in the United Nations’ description of the ocean as the “planet’s life support”(8)United Nations, ‘Goal 14: Conserve and Sustainably Use the Oceans, Seas and Marine Resources’ UN Sustainable Development Goals, https://www.un.org/sustainabledevelopment/oceans/ accessed 13.05.2026 , given its important role in regulating the global climate and sustaining human life(9)Ibid n8 . Human dependency on the oceans is evident in the variety of functions that the ocean performs, including the absorption of carbon dioxide, storage of heat, facilitation of international trade, provision of food and employment, and supplying minerals and energy resources. The high seas have been described by the Natural Resources Defense Council (‘NRDC’) as a significant repository for the world’s biodiversity(10)Brian Palmer and Jeff Turrentine, ‘Finally, a High Seas Treaty to Protect the World’s Oceans’ (09.10.2025) Natural Resources Defense Council website, https://www.nrdc.org/stories/finally-high-seas-treaty-protect-worlds-oceans accessed 10.05.2026. However, despite their undisputed importance to life on Earth, scientific reports suggest that significant challenges remain in ensuring the effective protection of biodiversity in ABNJ(11)Brondizio, Eduardo; Diaz, Sandra; Settele, Josef; Ngo, Hien T, “Global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services”, IBPES, (2019), Global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (zenodo.org), accessed the 14.09.2024. In 2016, the First Global Integrated Marine Assessment ‘World Ocean Assessment I’ stated that the oceans are subject to pervasive impacts of human activities(12)United Nations, ‘The First Global Integrated Marine Assessment (World Ocean Assessment I)’ (2016) UN, https://www.un.org/regularprocess/content/first-world-ocean-assessment accessed 02.05.2026 (part II, chapter 1, page 11), while the Sustainable Development Goals Report 2023: Special Edition has gone so far as to characterise the ocean as being in a state of emergency(13)United Nations, ‘The UN Sustainable Development Goals Report 2023, Special edition’ (2023) UN DESA, https://unstats.un.org/sdgs/report/2023/The-Sustainable-Development-Goals-Report-2023.pdf accessed 19.04.2026, page 40.
The Convention on Biological Diversity (‘CBD’)(14)Convention on Biological Diversity (adopted 22 May 1992, entered into force 29 December 1993, Nairobi) 1760 UNTS 79 (CBD) defines biological diversity as “the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems”(15)Ibid n14, Article 2. When applied to the high seas, marine biodiversity thus refers to the variety of ecosystems, species, and genetic resources present in the ABNJ(16)Alex D Rogers, Heather M Koldewey, Jennifer J Meeuwig and others, ‘The High Seas and Us: Understanding the Value of High‑Seas Ecosystems’ (2014) 23 Global Ecology and Biogeography 1, https://fisheries.sites.olt.ubc.ca/files/2023/01/high-seas-and-us.pdf accessed the 10.05.2026. This marine biodiversity is essential to maintaining a healthy ocean, including its ability to provide ecosystem services such as climate regulation(17)Intergovernmental Panel on Climate Change (IPCC), ‘Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC): Technical Summary (IPCC 2019), https://www.ipcc.ch/site/assets/uploads/sites/3/2022/03/02_SROCC_TS_FINAL.pdf accessed the 10.05.2026, page 58 and to sustain the provision of food through fishing activities(18)Ibid n16, page 43. More broadly, marine biodiversity underpins global environmental stability and human life, as its degradation risks undermining both ocean ecosystems and the vital services they provide. The pressures affecting the marine biodiversity are stated to generally be cumulative(19)Ibid n11, page 24 and transboundary in character, creating governance challenges that are difficult to effectively address solely through sectoral or unilateral action(20)See Cathryn C Murray, Megan E Mach and Rebecca G Martone, ‘Cumulative Effects in Marine Ecosystems: Scientific Perspectives on its Challenges and Solutions’ (2014) WWF‑Canada and Center for Ocean Solutions, https://awsassets.wwf.ca/downloads/cumulativeeffects updated_forwebupload_singlepages.pdf, accessed 12.03.2026, page 11. Accordingly, international cooperation is necessary to mitigate such global threats.
It has previously been argued that the legal framework for the protection and conservation of marine biodiversity is fragmented(21) Robin Warner, ‘Conserving marine biodiversity in areas beyond national jurisdiction: co-evolution and interaction with the law of the sea’ (2014), Frontiers in Marine Science, https://www.researchgate.net/publication/273515702_Conserving_marine_biodiversity_in_areas_beyond_national_jurisdiction_co-evolution_and_interaction_with_the_law_of_the_sea accessed 25.03.2026, page 3, particularly with respect to the protection of the environment and marine biodiversity in the ABNJ(22)‘Marine verneområder på åpent hav i Arktis’ (Master’s thesis, University of Bergen, 2020), https://nva-resource-storage-755923822223.s3.eu-west-1.amazonaws.com/13d0e700-47e4-4667-8769-43a9d594b101 accessed 10.05.2026, page 4. Fragmentation stems from the fact that the legal framework consists of various international agreements and conventions addressing different aspects of marine conservation, with insufficient coordination and gaps in the legal protection of the marine biodiversity in the high seas(23)Ibid n21. The protection of the marine environment has evolved through the adoption of both non-binding instruments and international conventions. UNCLOS established a legal framework that subjects State Parties to a positive obligation to protect and preserve the marine environment. Article 87 of UNCLOS sets out the freedom of the high seas, emphasizing that the high seas are for all to use, while Article 192 subjects all States to a general duty to protect and preserve the marine environment(24)Article 192 UNCLOS. In 2023, the historic BBNJ Agreement was adopted. The BBNJ Agreement supplements UNCLOS, aiming to protect marine biodiversity specifically in the ABNJ.
This thesis argues that the BBNJ Agreement can strengthen and further specify the responsibilities of flag States in relation to marine biodiversity in ABNJ. While the BBNJ Agreement does not impose new obligations on flag States, it gives concrete form to existing obligations under UNCLOS, including those relating to environmental impact assessments (‘EIAs’) on the high seas. As the obligations relevant to the protection of marine biodiversity in ABNJ extend beyond the scope of a single thesis, the analysis is necessarily selective and focuses on EIAs as a mechanism through which existing flag State obligations are implemented and given concrete effect. In the context of the high seas, where regulatory oversight is more limited than within areas of national jurisdiction, the significance of EIAs lies in their role in structuring the exercise of flag State due diligence under both UNCLOS and the BBNJ Agreement. EIAs therefore provide an interesting lens for examining how due diligence is operationalised in a regulatory context characterised by limited external oversight.
Responsibility for the enforcement of these obligations under the BBNJ Agreement, building upon the framework established by UNCLOS, rests primarily with the flag States exercising jurisdiction or control over the relevant vessel conducting activities in the ABNJ. For the purposes of this thesis, the concept of the flag State is understood in accordance with UNCLOS, which governs the attribution of nationality to ships and the scope of flag State jurisdiction and control. Flag States are the States in which vessels are registered and whose nationality they are entitled to fly. The BBNJ Agreement follows UNCLOS and does not alter the allocation of flag State jurisdiction. In this respect, UNCLOS confers upon flag States exclusive jurisdiction over their vessels on the high seas(25)Article 92 UNCLOS and imposes a duty to effectively exercise jurisdiction and control over administrative, technical, and environmental matters(26)Article 94 UNCLOS.
The jurisdictional allocation from Article 92 places flag States at the centre of the regulation of vessel-based activities on the high seas. The general rule of exclusive flag State jurisdiction entails responsibilities with respect to environmental protection, and in the context of international shipping, these responsibilities are exercised primarily through the implementation and enforcement of generally accepted international rules and standards developed by the International Maritime Organization (‘IMO’) as the competent international organization under UNCLOS(27)Article 211 UNCLOS. However, while the IMO has produced detailed regulation concerning vessel-source pollution and maritime safety, the IMO’s engagement with the protection of marine biodiversity in ABNJ has traditionally been indirect and fragmented, which is a part of the regulatory gaps which the BBNJ Agreement seeks to fill.
Article 91 of UNCLOS requires the existence of a genuine link between a vessel and its flag State. This is a requirement that has brought about extensive debate(28)See Eduardo Cavalcanti de Mello Filho, ‘From ‘Flags of Convenience’ to ‘Flags of Deceit’: The Future of the Law Governing the Nationality of Ships’ (2025), Cambridge University Press, International & Comparative Law Quarterly 121; and Nivedita Hosanee, ‘A critical analysis of flag State duties as laid down under Article 94 of the 1982 UNCLOS’ (2009) UN Division for Ocean Affairs and the Law of the Sea https://www.un.org/depts/los/nippon/unnff_programme_home/fellows_pages/fellows_papers/hosanee_0910_mauritious.pdf accessed the 25.03.2026, particularly in relation to flags of convenience, flags of deceit, and the effectiveness of flag State control. Questions concerning the adequacy of the genuine link requirement, as well as related enforcement or compliance gaps within the flag State system, while highly relevant to the effectiveness of international maritime regulation, fall outside the scope of this thesis. This thesis focuses on the development of flag State obligations under the BBNJ Agreement, understood as elaborating and operationalising existing obligations under UNCLOS in relation to the protection of marine biodiversity in ABNJ.