A map of some southern MPAs

X-marks the spot: Why are some large, remote marine Protected Areas so oddly shaped?

A bold, ambitious plan to protect the ocean is underway. 30 by 30 aims to secure strong environmental protection for 30% of the ocean by 2030. To do this, nations are creating new large remote Marine Protected Areas (MPAs) that cover huge swaths of their exclusive economic zones (EEZs) and preclude exploitation within these regions. 

But strong protection often comes with compromises, resulting in carve outs within MPAs that permit commercial and recreational exploitation, as well as traditional use. While most large remote MPAs are generically blob-shaped, with borders that extend to the limits of an EEZ, forming a 200-mile buffer around a landmass, for some, this careful balance between environmental needs and commercial concerns has resulted in curious and novel shapes. 

Among the global map of large Marine Protected Areas, one stands out as exceptionally distinctive. The Prince Edwards Islands Marine Protected Area in the Indian Ocean south of the South African Coast is uniquely Y-shaped. It is impossible to look at the curious borders of the Prince Edward Island MPA and not wonder what confluence of political, environmental, geologic, and practical considerations went into determining its boundaries. 

The shape of this MPA practically begs observers to ask “why?”

The Prince Edward Islands (not to be confused with Prince Edward Island, the Canadian province) are a small group of subantarctic islands in the Indian Ocean 2,000 kilometers south-east of Cape Town, South Africa. At 180,000 square kilometers, it is South Africa’s largest Marine Protected Area and is among the largest protected areas in the world.  The MPA is home to penguins, orcas, southern elephant seals, fur seals, and a large population of Patagonian toothfish, as well as several whale species. Within this MPA are over 40% of Wandering Albatross nesting sites.

Protecting these islands and the waters surrounding them involved creating a series of ocean zones that reflect a balance between ecosystem protection and commercial fishing. The central islands have a 12 kilometer sanctuary buffer to fully protect nesting sites and Patagonian toothfish, four restricted zones with limited fishing, and a control zone that connects the sanctuary to the restricted zones via ocean corridors. 

The most striking feature of the Prince Edward Island Marine Protected Area, its distinctive Y shape, emerged from this need to balance multiple habitat protections with commercial needs. Each of the four restricted zones represent different ecosystems in need of protection–the South-West Indian Ridge, the Islands, the seamounts of the Africana Rise, and the abyssal plain–and the natural pathways of migratory species. The arms of the Y stretch out across the foraging paths of albatrosses and elephant seals, with restricted zones assigned where those features overlapped. 

The shape of the Prince Edward Islands MPA asks “why?” and the answer is “because that is where the species in need of protection (on average) travel”.

The Prince Edward Islands Marine Protected Area isn’t the only MPA who’s uncommon shape reflects the core rationale behind the MPA’s creation. The Nazca-Desventuradas Marine Park, one of the largest and most well-protected MPAs in the Pacific, contains a large wedge carve out which resembles nothing so much as the world’s largest Pac Man. Nazca-Desventuradas Marine Park is a fully protected MPA, there’s no fishing or resource extraction within the protected area, and the protected area is huge. At almost 300,000 square kilometers, it is the largest marine protected area in the Americas and accounts for 8 percent of Chile’s Exclusive Economic Zone. 

“The new Nazca-Desventuradas Marine Park is a gift from Chile to the world,” said Dr. Enric Sala in a press release issued by Oceana. “It contains pristine underwater environments like nothing else in the ocean, including deep underwater mountains with species new to science, abundant giant lobster and a relict population of the once-thought-extinct Juan Fernández fur seal.”

The large carve out, which lends the MPA its distinctive shape, is, according to one source from Oceana, to allow swordfish fishing to continue. To the south of this massive protected area, a designated but not yet implemented marine protected area, Mar de Juan Fernández Marine Park, surrounds the Juan Fernández Islands. These two MPAs, together create a square, contiguous carve out, mirrored in both parks, which covers large portions of the Chilean abyssal plain. 

Within the discussions for almost all recent large remote marine protected areas is a recognition that strong protections today may impede future deep-sea mining ventures. Though not explicitly stated in the founding documents for these MPAs, the carve out areas for both Nazca-Desventuradas and Mar de Juan Fernández contain polymetallic nodule deposits (within Mar de Juan Fernández) and ferromanganese crusts (within Nazca-Desventuradas), which occur wholly within Chile’s Exclusive Economic Zone. 

A more clear case of MPA carve outs for future resource extraction lies in the South Atlantic. The Tristan da Cunha Marine Protection Zone, currently designated but not yet implemented by the British government, surrounds Tristan de Cunha, the most remote inhabited archipelago in the Atlantic. Thanks to the position of the two inhabited islands, which retain their inshore fishing rights, the MPA appears on maps as a gigantic figure-8. But the necessary holes around inhabited islands aren’t the most interesting carve outs. 

The Tristan da Cunha Marine Protection Zone is part of a network of UK protected areas that form  the fourth largest marine protected area in the world. Tristan da Cunha Marine Protection Zone covers over 90% of the exclusive economic zone surrounding four islands within the UK overseas territories of Saint Helena, Ascension and Tristan da Cunha. The MPA protects the habitat for rockhopper penguins and albatrosses, as well as beaked and fin whales, and subantarctic fur seals and elephant seals.  

While the Tristan da Cuhna Marine Protection Zone falls within the larger management plans of St. Helena, Ascension and Tristan da Cuhna, the MPA surrounding Ascension and St. Helena follow the boundaries of each islands’ EEZ, only Tristan da Cuhna has designated carve outs within the EEZ. These carve outs cover a portion of four seamounts within the protected zone, allowing access to offshore fishing. However, in addition to fishing rights, at least one of these carve outs covers the largest cobalt-rich crust deposit in the region. 

Though explicitly excluded to allow offshore fishing, the seamount carve outs of Tristan da Cunha also include the largest deposits of cobalt-rich ferromanganese crusts within the islands’ EEZ. A year after announcing the Saint Helena Marine Protection Zone and the intent to expand protections to Ascension and Tristan da Cuhna, the UK reasserted its Minerals Vesting (Tristan da Cunha) Ordinance of 1951, declaring the seabed resources surrounding the archipelago as subject ot control of the Crown. Whether or not future deep-sea mining weighed heavily on the ultimate designation and assessment of carve outs, the future expansion of the industry will likely explore the potential of these unprotected pockets within the UK’s Exclusive Economic Zone.

Featured image: taken from Marine Protection Atlas.

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