The high seas, or international waters, encompasses all areas beyond 200 nautical miles (nm) of shore, which in total constitutes one-half of the world’s surface area. Not only is this a massive area, but also hosts a diversity of life, with species ranging from sharks and albatrosses, to tuna and sea turtles using the high seas on a regular basis (Harrison et al. 2018). Importantly, many species from these groups are in severe decline (here), and therefore it may not suffice to protect them while within national waters.

When many of us think of the high seas the first thing that comes to mind is legal freedom. These are the places where clandestine activity is undertaken, from pirate radio stations (here), to providing abortion procedures to women from countries where they are illegal (here). But with so much attention being paid at the moment to marine environmental issues like plastic waste and overfishing, it might be helpful to know what the high seas actually are, legally-speaking, and how this relates to nature management.

Mare liberum

In 1609, the Dutch jurist Hugo Grotius declared in a legal treatise that the oceans are Mare liberum, or ‘free seas,’ and therefore open to navigation. This went directly in the face of the status quo at the time under which colonial powers, namely Spain and Portugal, were claiming sovereign control over entire ocean basins (here). Englishman John Selden coined this opposing worldview Mare clausum, or ‘closed seas,’ in a 1635 rebuttal of Grotius, wherein he claimed that the seas are as amenable to territorial appropriation as is land.

A centuries-long tug-of-war ensued, culminating in 1982 when the United Nations Convention on the Law of the Seas (UNCLOS) was struck. This landmark piece of international law reflects a solidified balance between Mare liberum and Mare clausum, by bringing nearshore areas under national jurisdiction, while allowing distant, offshore waters to remain “free”. Specifically, UNCLOS mandates that waters within 12 nm of shore be ‘territorial waters,’ wherein nations have full jurisdiction, and waters within 200 nm be ‘exclusive economic zones’ (EEZ), wherein nations have resource extraction rights as well as full conservation responsibility.

Upon adoption of this legal framework, one-third of the world’s oceans came under direct jurisdiction of the world’s coastal nations, while the remaining two-thirds became so-called Areas Beyond National Jurisdiction (ABNJ). Under UNCLOS, any and all actors have equal right to use and access these areas, à la Mare liberum. However, with freedom comes responsibility and UNCLOS does also stipulate that all high seas actors are responsible for the preservation and protection of the high seas environment.

So how is this done, in practice?

Management and conservation

UNCLOS requires that states “adopt measures” and “collaborate” to conserve marine life. In essence, if entities under a state’s jurisdiction, like fishing fleets, use the high seas then the state is responsible for coordinating with other parties to regulate the activity and mitigate impacts. In the case of fisheries, this takes the form of Regional Fisheries Management Organizations (RFMOs), which provide a forum for states to discuss not only catch regulation, but also for conservation-related issues to be raised. One major conservation issue related to fishing in the high seas is the incidental catch of non-target species (termed “bycatch”), and it is at meetings of RFMO members that these issues can be raised and solutions adopted. Nevertheless, organizations such as RFMOs have as their mandate only to manage target fish species, and therefore any impacts of their policies on other marine biodiversity, positive or negative, are only side effects.

Another instrument for conserving high seas biodiversity is the establishment of explicit areas in which human activities are limited. These can range from temporary fisheries closures areas, as implemented by RFMOs, to Marine Protected Areas (MPAs) wherein a broader range of human activity may be restricted. At the moment, the only legal frameworks in place with the mandate to establish MPAs in the high seas are regional seas conventions, such as the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR). Under the mandate of the Antarctic Treaty System, CCAMLR has led to a number of protective measures for creatures inhabiting waters south of 60° S, including protected areas as well as comprehensive restrictions on resource extraction (Ban et al. 2014).

The future: Mare sustinendum

Since the adoption of UNCLOS in the 1980s, humanity’s interest in resource use in the high seas has increased in scope and scale. In parallel, interest in whole-ecosystem management has also grown; which, in part reflects an improved scientific understanding of the ocean environment and its interconnected and dynamic nature (here). While the regional structure of CCAMLR in the Southern Ocean provides examples of near comprehensive, international nature management, there remain large swathes of the high seas lacking such regional-based coordination (Ban et al. 2014). Therefore, what is likely the only sure-fire way to achieve this goal is to implement a comprehensive legal framework for the high seas, which can reflect our evolving management values, and take advantage of an ever-improving understanding of the marine environment (Wright et al. 2019).

This framework, referred to in policy circles as the International Legally Binding Instrument (ILBI) is a veritable ‘Holy grail’ for international nature policy, and has been sought after since the initiation of the UNCLOS process in the 1970s (Ban et al. 2014, Wright et al. 2019). To this end, the UN in 2018 and 2019 convened sessions for member states to discuss the possibilities and challenges of adopting an ILBI for the high seas. At the most recent meeting, major sticking points among members included the use of marine genetic resources, specifics on how benefits would be equitably shared among benefactors, as well the handling of intellectual property rights (here).

Grotius’ idea that the high seas should be open and free to all was a revolutionary one. However, this idea relied on a 17th century perspective of scale and human enterprise. At that point in time, undertaking activities such as fishing with baited hooks on lines 100 km in length (here), and deep-sea mining using Remotely Operated Vehicles (ROVs; here) at depths of 3.7 km were either unimaginable or practical impossibilities. The high seas are no longer out of reach nor invulnerable, and marine biodiversity are starting to pay the costs (here). Therefore, it is time we use our updated perspective to lay out specific, integrated roles for the sustainable management of the high seas to the benefit of everyone.

Mare sustinendum anyone?