Little known, the Saya island of Malha is one of the most important places on the planet for its ecosystem and its role in ‘regulating the environment’. The island is under serious threat from overfishing and overexploitation of its resources. Several organisations are warning and working to protect what is considered one of the planet’s marine ‘lungs’.
Located in the Indian Ocean between Mauritius and the Seychelles, the island of Saya de Malha owes its name to the Portuguese sailors who discovered it nearly five centuries ago. It is thought that the name refers to the undulations of the seagrass beds beneath the surface. Its surface area (around 40,000 km²) is equivalent to that of Switzerland. It is known as the ‘invisible island’, and even the largest invisible island in the world, because of its many hidden underwater areas. The submerged parts of the island are very shallow (less than ten metres of water in some places). Sailors avoid getting too close to the coast because of the variable and uncertain heights of the shoals, which can damage ships. On the other hand, they are home to a rich biodiversity of plants and animals, including turtles, rabbitfish, parrotfish, spotted dolphins and lizardfish. Blue whales, humpback whales and sharks come here to breed.
Saya de Malha is far from the nearest coast, which is more than 300 km away. For many years, little research has been carried out on this island, possibly because of its isolation and geographical position in international waters. Some species have yet to be discovered. The first scientific study was carried out in 1997.
Saya de Malha is said to have one of the largest seagrass beds in the world. The vast expanses of grass play a crucial role in cleaning up the atmosphere. Its capacity to absorb carbon is around 35 times greater than that of the Amazon rainforest. This vast herbarium cleans both air and water. According to a study published in Nature Scientific Reports in 2021, the grasses trap certain types of waste, such as microplastics, and keep them in the sediment. A report published in 2021 by the University of California at Davis found that seagrass beds also protect against erosion. Their role is fundamental to maintaining the ecosystem, providing shelter for many endangered species, some of which are at risk of disappearing if seagrass beds are reduced.
However, they make up only one tenth of one per cent of the seabed, about 0.15 per cent. Yet they are considered the ‘lungs of the ocean’. In 2022, on 23 May, the United Nations General Assembly will designate 1 March as World Seagrass Day.
The island’s seabed also contains nodules, which are very rare and grow very slowly. They are prized for the elements they contain, which are used to make batteries, computers and mobile phones.
Because of its wild and isolated nature, several people have tried to build floating cities around Saya de Malha. These projects have not survived the elements or the vagaries of the sea. Others wanted to escape their countries and their administrative or financial problems. The island is on the high seas, which means it is outside the jurisdiction of the government, which is not in its favour.
The waters around the island contain reserves of oil, gas and precious metals (titanium, cobalt and nickel). Buried at depths of several thousand metres, their extraction by machines such as excavators is destroying the marine environment.
Climatic hazards have threatened the island’s marine biodiversity, particularly in 1998.
The coral reefs were severely damaged by bleaching, a worldwide phenomenon. Although the reefs have been repaired, the island’s shoals (sometimes regular elevations of the seabed visible at low tide) are still threatened by climate change, which is becoming increasingly significant.
The lack of knowledge about the island of Saya de Malha and its isolation mean that the crimes that take place in its waters are not well known. Although the island is little known, its resources are unfortunately the victims of overfishing, illegal fishing, overexploitation and, as a result, environmental degradation. Unfortunately, there is no jurisdiction over international waters and despite the United Nations Convention on the Rights of the Sea, legal action is extremely complicated.
Animal species are threatened by overfishing, especially tuna and sharks. Many fishing vessels, mainly from Sri Lanka, Taiwan Area, China and Thailand, head to Saya de Malha to overfish in cruel conditions. Nets left in the sea endanger species, and fishing techniques damage the seabed, threatening the marine balance. Scratching the bottom brings sediment to the surface, blocking the sunlight that seagrass beds need. Outside the jurisdiction, many fishing vessels evade penalties. In the wake of these incidents, environmentalists say not enough is being done to restore seagrass beds. Their disappearance is threatening to cause an ecological disaster.
The shark population has declined at an alarming rate. At the end of 2002, scientists from Explorations de Monaco, a marine conservation organisation linked to H.S.H. Prince Albert II of Monaco, went to Saya de Malha to film sharks and carry out studies. After three weeks they found no sharks, which is unusual. The Saya de Malha shoals are a glaring example of how difficult it is for the authorities to punish crimes on the high seas.
Many people have contributed to the degradation of the banks of Saya Malha. There are fishermen who specialise in shark fins, trawlers and companies that search the seabed for nodules and precious metals, drift fishermen who go too far from the coast, and yacht owners. The most dangerous to the ecosystem are those who overfish and destroy the seabed.
Scientists believe that one of the biggest threats to Saya Malha is a fleet of more than 200 boats from 10 different countries, including Sri Lanka, Taiwan Area, China and Thailand, which have been heading into the deep waters around the island to catch various species of tuna, sharks and other fish to make meal, which is then used to feed animals (poultry, pigs). These numerous vessels will operate between 2021 and 2024.
In 2015, around fifty Thai vessels visited the island’s shores to fish for horse mackerel, which is processed into fishmeal. More than half of them did not comply with fishing regulations. A Greenpeace investigation found that they were also targeting Saya de Malha’s sharks. Unfortunately, as the number of Thai vessels has declined over the past decade, so has the number of sharks. Some have been punished, mainly for illegally transporting shark fins and carcasses, and for falsifying fishing licences and reports. But this has not stopped illegal fishing.
Difficulties in enforcing sanctions also stem from the oil and mineral exploitation contracts signed by the Mauritian and Seychellois authorities, despite the disastrous environmental consequences (oil spills, soil erosion, waste dumping).
In September 2024, an agreement was signed between the two governments to begin exploration on the banks of the Saya de Malha.
Sharks play an essential role in maintaining marine biodiversity by acting as regulators. Their disappearance would mean the disappearance of other species. They are highly valued for their fins. The way they are caught is particularly cruel: their fins are cut off before they are thrown back into the deep sea alive, condemning them to drown and a slow, painful death. The International Union for Conservation of Nature estimates that two-thirds of Sri Lanka’s shark and ray species are threatened with extinction. The decline in their numbers in territorial waters has led fishermen to venture into international waters. In particular, Sri Lanka exports shark fins to Hong Kong. According to UN Comtrade estimates, this has increased dramatically. From 28 tonnes in 2013, 110 tonnes will be exported by 2023. Vessels are difficult to track as some do not report their position, sometimes revealing the illegality of the activity and hampering marine conservation efforts. Although Sri Lanka has banned oceanic shark fishing and finning, many vessels continue to overfish. In 2024, IMUL-A-0064 KMN was subject to a verification process by the Sri Lankan authorities. Its cargo included more than half a tonne of shark carcasses with fins cut off.
Overfishing in the international waters around Saya Malha reveals other dangers. Lost on the high seas, far from the coast and exposed to bad weather and storms, the fishermen also face disease, some are overfished, many lose their lives and never return.
Despite the isolation of the island and the difficulties of enforcing justice, several associations and organisations are working to bring the world’s attention to Saya de Malha, its environmental problems and the dangers it faces. Global Fishing Watch promotes transparency in human activities at sea. The Environmental Justice Foundation fights for environmental safety. Greenpeace led an underwater demonstration at Saya de Malha in 2021, filming messages on placards warning of the dangers of extracting minerals from the sea.
In 2025, The Outlaw Ocean Project, an investigative journalism NGO, carried out a major investigation, published under the title ‘Robbing a bank when no one’s looking’, which exposed the challenges facing the Saya island of Mahla with great indifference. Its work was picked up by several media.
Monaco Explorations plays an important role in the protection of Saya de Malha. In 2022, during the Ocean India mission aboard the research vessel S.A. Agulhas II, they carried out research to document the rich fauna and flora of the island’s shores and noted the abnormal absence of sharks. Several scientists, researchers, artists and students took part. The organisation serves H.S.H. Prince Albert II of Monaco, who is committed to protecting the oceans. The main objective of the 2022 Indian Ocean mission was to protect the Saya de Malha.
Finally, the IRD, Institut de recherches pour le développement, is working to achieve the UN’s ODD 2030 goals and protect the environment. It was part of the Indian Ocean 2022 mission.
The Southern Indian Ocean Fisheries Agreement (SIOFA) was signed in 2006 and came into force in 2012. It is a regional fisheries management organisation responsible for conserving high seas stocks other than tuna. It sets fishing quotas to prevent illegal catches. APSOI operates in the Saya de Malha waters.
However, its jurisdiction does not extend to countries that have not signed the agreement. Sri Lanka is not a signatory.
Several countries are now calling for the island to be protected, with a view to making it a ‘high seas sanctuary’ under the High Seas Treaty. Surveillance and search missions would also help limit or even reduce criminal activity. Raising awareness of the vital importance of this marine area and the seagrass meadows it contains would help to improve the conservation of flora and fauna, including endangered species. Environmentally friendly measures and stricter penalties for overfishing should be introduced by local governments to reduce illegal fishing and ultimately enable the rehabilitation of the sharks. The Mahla Saya beds are an important breeding and migratory area for a number of species. Protecting this area also helps to protect the Indian Ocean environment.
