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The Chagos Archipelago - New Web Site Launched

The Chagos Islands - The World's Largest Marine Protected Area

The United Kingdom's (UK) Chagos Archipelago, located in the middle of the Indian Ocean, is the world's largest coral atoll. It is often compared to the Galapagos or Australia's Great Barrier Reef in terms of its importance as a hotspot of biodiversity. As one of the most pristine and resilient tropical marine environments on Earth, the Chagos Archipelago is home to 17 species of breeding seabirds, about 1,000 species of fishes, 220 species of corals, and two species of endangered sea turtles. Leading scientists from around the world support the UK designation of this immense area as a no-take marine protected area. Opposition, however, has come from the native islanders (Chagossians) who were evicted between 1967 and 1971 to make way for a US military facility on the largest island of the archipelago, Diego Garcia. The Chagossians have been battling the British government in the UK courts for the right to return to the islands.

   British Indian Ocean Territory (BIOT) Coat-of Arms
British Indian Ocean Territory (BIOT) Coat-of Arms


This professional exchange discussion is a fairly balanced airing of opinions and ideas on environmental protection and conservation throughout the Chagos Archipelago, as well as a discussion of social issues involving the displacement and return of the Chagossians. It is important to note that while this professional exchange was ongoing, the UK had yet to announce a decision on designating the Chagos Archipelago as a no- take marine protected area (MPA).

On April 1, 2010, the United Kingdom's Secretary of State designated the Chagos Archipelago as a no-take marine reserve. This declaration makes it the largest marine protected area in the world, totaling more than 210,000 square miles (545,000 square kilometers), and doubles the total global area of marine reserves.

Click here for a listing of discussion participants

Click here to download the complete unedited discussion (pdf, 143 kb)


The Chagos Archipelago in the middle of the Indian Ocean
The Chagos Archipelago in the middle of the Indian Ocean

Introduction and Background

Middle Brother Island
Middle Brother Island, one of the many uninhabited Chagos islands (Photo: Courtesy of the Chagos Conservation Trust/ Anne & Charles Sheppard)

The islands of the Chagos Archipelago were discovered by Portuguese explorers in the early sixteenth century and claimed by France in the eighteenth century as a possession of Mauritius. African slaves and Indian laborers were brought to the islands to establish copra plantations on the main island of Diego Garcia. In 1810, Mauritius was captured by the British and ceded to the United Kingdom (UK) four years later. Then, in 1965, the UK split the Chagos Archipelago from Mauritius and combined it with three islands from the Seychelles to form the British Indian Ocean Territory (BIOT). In 1976, however, the Seychelles attained its independence and the three islands were returned, leaving only the six main island groups of the Chagos Archipelago to comprise the BIOT.

In 1966, the British Government purchased and closed down the copra plantations and extradited the entire population of Chagossians (also called "Ilois") to Mauritius. Five years later, the UK and the United States signed a treaty, leasing the island of Diego Garcia to the American military for the purposes of building a large air and naval base. Work on the military base began with several long range runways and a harbor suitable for large naval vessels.

U.S. Air Force Base on Diego Garcia
U.S. Air Force Base on Diego Garcia (Photo: United States Air Force (USAF))

The evicted Chagossians, principally residing in Mauritius, the Seychelles, and the UK, have continually asserted their right to return to Diego Garcia.  The British Government established a trust fund as compensation for the displaced islanders, but the Chagossians continue to pursue a series of lawsuits against the British Government seeking further compensation and the right to return to the territory. In 2006 and 2007, British courts invalidated immigration policies that had excluded the islanders from the archipelago but upheld the special military status of Diego Garcia. The following year, the House of Lords, as the final court of appeal in the UK, ruled in favor of the British Government by overturning lower court rulings and finding no right of return on the part of the Chagossians.

It is uncertain whether the Chagossians will ever be permitted to return to Diego Garcia.  However, should resettlement occur, the terms of the no-take marine reserve now established in the Chagos Archipelago would need to be adjusted to allow, for example, sustainable subsistence fishing by the residents.

A healthy reef in the Chagos Archipelago
A healthy reef in the Chagos Archipelago (Photo: Courtesy of the Chagos Conservation Trust)

The Chagos Archipelago, at the southern end of the Laccadives-Maldives-Chagos atoll chain, is an isolated group of coral atolls and reefs in the central Indian Ocean (centered at about 6°S, 72°E),  about halfway between Africa and Indonesia. It is comprised of five atolls, 10 other shallow reef banks and submerged shoals, about 55 uninhabited islands, and Diego Garcia, which houses military and civilian contractors at the joint UK-US military facility.

The Chagos Archipelago contains the world's largest coral atoll and has one of the most pristine and healthiest shallow-water reef ecosystems in the world. It also supports a number of deep sea habitats, including deep trenches, oceanic ridges and sea mounts, each of which harbors specially adapted species.

Chagos contains up to one-half of the healthy reefs in the Indian Ocean and is one of the most ecologically sound reef systems on the planet. Elsewhere in the Indian and Indo-Pacific Oceans, reefs are under pressure from the effects of massive human population growth and are nearly all in decline. Pollutant levels in Chagos waters and marine life, however, are exceptionally low, mostly below detection levels at one part per trillion, making it an appropriate global reference baseline. The ecosystems of the Chagos have thus far been resilient to coral bleaching and environmental disruptions. The archipelago and its surrounding waters support an incredible biodiversity, but it is this diversity that is under threat with at least 60 species on the IUCN (World Conservation Union) Red List of Threatened Species. The area is also critical for the repopulation of coral systems along the East Coast of Africa and to the recovery in marine food resources in sub-Saharan Africa.

reef in Chagos
(Photo: Courtesy of the Chagos Conservation Trust)

The uninhabited (except Diego Garcia Island), isolated, and centrally-located shallow water and deepwater ecosystems act as 'oases' and banks for marine and island species.  They are invaluable as stepping stones, crucial refuges, staging posts, and breeding grounds for marine biota and the richest diversity of seabirds in the Indian Ocean. The archipelago is the source of an abundance of larval and juvenile marine animals that drift or migrate long distances, restoring reefs and sustaining marine populations throughout the region.

Gold-spotted Trevally protected in the no-take MPA
Gold-spotted Trevally protected in the no-take MPA (Photo: Courtesy of the Chagos Conservation Trust)

Free of human disturbances, the archipelago's water is far clearer than most waters around coastal reefs, allowing corals to grow at deeper and cooler depths.  This also enabled the corals to survive a severe, temperature-related coral-bleaching event in 1998. Deeper corals provided a reservoir for larvae that replaced the dead corals at shallower depths. The Chagos reefs proved resilient and returned to good health, while many reefs in the broader Indian Ocean region did not recover.

With the creation of the Chagos Marine Protected Area (MPA), an area covering 210,000 square miles (545,000 square kilometers), the UK doubled the global coverage of the world’s oceans under protection. The MPA includes a no-take zone where all commercial fishing and deep-sea mining activities are banned.

Nesting bird populations in the Chagos Islands
Nesting bird populations in the Chagos Islands (Photo: Courtesy of the Chagos Conservation Trust)

In support of the argument to quickly designate the Chagos as a no-take MPA, one of the participants in this Professional Exchange (University of Warwick) stated that "Every ocean needs at least one set of reefs where no run-off, no dredging, no building, no fishing, no nutrient enrichment and no pollutant and pesticide release whatsoever takes place. For the Indian Ocean, the reefs of Chagos are the prime candidate, and perhaps are the only sensible possibility. In the late 20th century, there are now very few others which fit the bill."


Synopsis of Discussions

All participants in this discussion were concerned scientists and conservationists. Most differed in their views only with respect to the timing of the Chagossians return to the Chagos islands or the Chagossians rights to establish a viable economy based on conservative subsistence exploitation of local, living marine resources.

The first post to the Chagos Island discussion was brought by a participant who called attention to the United Kingdom's (UK) three-month public consultation on extending conservation protections for the Chagos Islands and its surrounding waters. He stressed the importance of the Chagos Archipelago as a large, still pristine tropical marine environment, comparable in importance to the Australian Great Barrier Reef and the Galapagos Islands. He also noted that the three main consultation options were (1) a complete no-take over the entire exclusive economic zone (EEZ); (2) complete EEZ MPA, zoned and with no-take in shallow waters but continued pelagic fishery; or (3) no-take over the reefs and shallow waters. Most leading scientific and non-governmental organizations (NGOs) supported the creation of the first option. However the Chagossians, as well as Mauritius (who claim the islands), were largely excluded from initial discussions and have made clear that while they support conservation, they do not agree with a total no-take zone everywhere. A fourth option suggested was to develop an MPA with very large no-take elements but with a provision for continued conservation under future political scenarios, such as the Chagossians returning or Mauritius gaining sovereignty over the area. (The UK government has promised this once the military base is no longer needed.)

Diego Garcia Island
Diego Garcia Island (Photo: USAF)

Another participant, who set the tone for subsequent discussions, thought it "disingenuous" to propose the creation of this protected area without mentioning how, and in what manner, the former occupants of the archipelago were removed. He noted that when the UK and the US planned and established the Naval Support Facility at Diego Garcia Island, there was no apparent input from or consultation with the soon-to-be-displaced islanders. He raised the question of Chagossians' rights to return to their homes, human rights, and the role of scientists and conservationists in a discussion that should focus on social considerations. He opined further that creating a wholly exclusionary conservation zone might be ill-advised, as a full no-take conservation zone "will eventually be overtaken, anyway, through encroachment of human activities and abandonment of conservation laws by future governments. Whereas, having an established community with a vested interest toward conservation would create a stronger and longer lasting presence in the Chagos islands to ward against encroachment."

Still another participant noted that he could "not see any circumstances in which it would be disadvantageous to anyone (other than ocean fishing fleets) to have this large reef system protected in their entirety now, given that in the event of a change in sovereignty or settlement, conservation arrangements could be modified. Designating these reefs, islands and surrounding waters now as fully protected would safeguard them for the future, whatever that may be."

A different participant, who championed the Chagossians right to return to the islands, noted that the Chagossians were ill-served by their unwilling removal and that a no-fishing declaration would prohibit their only means of livelihood should they return. He inquired as to why the government was in such a hurry to designate the island area as an MPA. He noted that the coral reefs and adjacent ecosystems have remained in remarkable health for the last 40 years. He also mentioned that extra immediate protection for this remote area would probably not be achieved by the designation, as there exists a lack of real enforcement resources. In reply, a proponent of immediate protection of the Chagos Archipelago stated that "the goal is to fully protect the near-pristine coral reef and other marine environments of the central Indian Ocean, and anything that would delay or derail that effort should be avoided. Protecting this area would be an enormous contribution to the conservation of the world's marine environment. The UK Government has no other marine area under its jurisdiction that is as rich biologically, which could be protected as cheaply, or which would be so universally beneficial Conservation now would be to the advantage of any future resident population, should things change in that respect, and to no one's disadvantage, least of all to other residents of the Indian Ocean."

Boiled down to its simplicity, the UK had two options related to declaring the Chagos Archipelago a MPA: (1) the UK could delay any decision on the MPA, considering the plight of the Chagossians and future political changes, or (2) the UK could quickly declare the area a MPA because of continued damage from (legal) fishing to numerous species and, partly, because the opportunity to designate the area as a MPA might not recur.


Final Chapter

Chagos Island
(Photo: Courtesy of the Chagos Conservation Trust)

On April 1, 2010, the UK Foreign Secretary, David Miliband, announced the creation of a Marine Protected Area (MPA) in the British Indian Ocean Territory. This included a "no-take" marine reserve where commercial fishing was banned.

I am today instructing the Commissioner of the British Indian Ocean Territory to declare a Marine Protected Area. The MPA will cover some quarter of a million square miles and its establishment will double the global coverage of the world's oceans under protection. Its creation is a major step forward for protecting the oceans, not just around BIOT itself, but also throughout the world. This measure is a further demonstration of how the UK takes its international environmental responsibilities seriously. The territory offers great scope for research in all fields of oceanography, biodiversity and many aspects of climate change, which are core research issues for UK science.

I have taken the decision to create this marine reserve following a full consultation, and careful consideration of the many issues and interests involved. The response to the consultation was impressive both in terms of quality and quantity. We intend to continue to work closely with all interested stakeholders, both in the UK and internationally, in implementing the MPA.

I would like to emphasise that the creation of the MPA will not change the UK's commitment to cede the Territory to Mauritius when it is no longer needed for defense purposes and it is, of course, without prejudice to the outcome of the current, pending proceedings before the European Court of Human Rights.

Note: Marine and wildlife filmmaker, Jon Slayer, made a video highlighting the incredible biodiversity of the Chagos. The three-minute film can be viewed on the website


Updated April of 2012.

The Chagos Archipelago - New Web Site Launched

A new website has been launched giving access to detailed information about the Chagos (also known as the British Indian Ocean Territory).

The website provides a unique reference point to a wide range of material (scientific, general factual, legal, and human rights). It is intended to be a 'real time' resource, being updated with material obtained from the British Government and other sources. A wide range of documents can be freely downloaded. There is also an extensive research bibliography.

The site is essential reading for any scientist who wishes to work in the area, or anyone interested in the Chagos Archipelago. It also contains details of known research, past and current in the Chagos, and discussions of research areas that may be controversial.


Information Sources

Chagos Environment Network

Consultation Report: Whether to Establish a Marine Protected Area in the British Indian Ocean Territory

Wikipedia: Chagos Archipelago

CIA World Factbook

Christian Science Monitor

PEW Environment Group
Global Ocean legacy

British Indian Ocean Territory

Chagos Conservation Trust US