Decision-making for management of the Chagos Islands under Mauritius

Adam Moolna, School of Life Sciences, Keele University, Staffordshire, England

Phathutshedzo Mukwevho, Research Unit for Environmental Science and Management, North-West University, Potchefstroom, South Africa

Reece C. Alberts, Research Unit for Environmental Science and Management, North-West University, Potchefstroom, South Africa

Francois P. Retief, Research Unit for Environmental Science and Management, North-West University, Potchefstroom, South Africa

Sovereignty of the Chagos Islands will soon be formally transferred from the United Kingdom to Mauritius, creating uncertainty as to how future developments and environmental impacts will be managed. A business-as-usual approach should be maintained pending implementation of a thorough environmental and social impact assessment framework. Possible alternatives for future management, including commercial activities and resettlement, should be reviewed in an open and transparent process engaging all stakeholders. Changes in management would be political decisions – but well-informed choices need the best possible decision-making approaches. An inclusive and environmentally sustainable future for both the environment and people depends on it.

Sovereignty transfer

A final agreement for sovereignty transfer of the Chagos Islands from the United Kingdom (UK) to Mauritius was signed on behalf of the two governments in May 2025.

The islands, except for the United States (US) military base on Diego Garcia, have been uninhabited since 1973. Commercial fisheries in the surrounding seas ceased with the UK declaration of Chagos as the world’s largest no-take Marine Protected Area (MPA) in 2010. The British Indian Ocean Territory (BIOT) administration of Chagos has, however, overseen a continuing programme of extensive environmental research, including expedition-based ecological restoration activities on the islands. The coral reef ecosystems are of global significance due to their exceptional biodiversity, pristine condition, and role as a crucial reference site for scientific research.

The sovereignty transfer agreement is expected to come into force before the end of 2025, upon acceptance by the two nations’ legislatures. The agreement includes payments from the UK to Mauritius averaging around £100 million per year that could be ringfenced for investment in management of Chagos, support for transition to a Mauritian MPA, and addressing the Chagossian community.

Informed decision-making

The coming months present a critical window for the Government of Mauritius in shaping approaches for future management of Chagos. There is uncertainty about whether the uninhabited and undeveloped status will continue, especially as resettlement options have long been campaigned for by displaced Chagossians.

In the immediate future, a business-as-usual (BAU) scenario of continuing the management framework and limited development status as under the BIOT administration should be maintained by Mauritius until, and unless, comprehensively informed decision-making supports any change. Environmental, sociopolitical, and economic implications need careful consideration.

Whether to make any change in management, including whether to pursue development or establish population centres on the islands, is ultimately a political decision for Mauritius. Whatever course, Mauritius needs to make well informed choices using the best possible decision-making approaches and appropriate evidence.

To achieve this, it is recommended that such decisions be informed by best practice environmental assessment (EA). Purposefully designed EA for Chagos is crucial for a sustainable future and to proactively address identified weaknesses in Mauritius’ existing EA frameworks.

The future of the Chagos Islands should be of significant interest to the EA and sustainable development communities globally. It presents a rare opportunity to design an EA and decision support framework from scratch for near-pristine environments facing potential development. Any development would likely be under the close control of government and a limited number of actors, creating an ideal context for the adoption of best practice EA integrated with MPA management.

Considerations to be progressed

We are currently working on an academic paper proposing how Mauritius could approach this, drawing on the current state-of-the-art in EA approaches for development decision-making and protected areas management. Importantly, we will not be advocating for any one specific scenario but instead outlining how Mauritius can comprehensively consider the evidence and arguments from the broad spectrum of stakeholder perspectives and reconcile conflicts in its decision-making processes.

The Government of Mauritius should integrate best practice EA with development decisions to effectively incorporate biodiversity conservation perspectives, ocean-focused sustainability, existing environmental evidence and expertise, and sociopolitical considerations including the exiled Chagossian community. This should be done in an inclusive and transparent manner.

Long-term management must also be adaptive to changing circumstances, refined values, and new evidence informing decisions integrating environmental, social, and economic costs and benefits. The global climate and ecological emergencies present a changing baseline over the remainder of the 21st century,  and beyond, for future scenario consideration. And decision-makers should embrace the importance of inter-generational equity, longevity, and restorative justice. An overarching and iterative strategic environmental and social impact assessment framework should therefore consider how impacts unfold and can be managed through to the year 2100 in detail and beyond this in more general terms.

Alternative long-term scenarios including resettlement

Mauritius may wish to review the BAU scenario in comparison with a limited number of alternative long-term scenarios. The absence of people and the absence of commercial activities are the two dominant parameters in determining the current state of human impacts and options, including ecological restoration and climate adaptation measures, for management.

Most prominently, Mauritius may wish to explore options for resettlement. What such a scenario might include needs extensive engagement with stakeholders, not least the Chagossian community currently left in uncertainty as to their future citizenship and options. A realistic scenario may be creation of a permanent settlement on one island of either Peros Banhos or Salomon atolls. This could act as a hub for management and activities across the islands and reefs more broadly.

Ongoing access to any settlement, however, might require construction of an airstrip with associated impacts. This would be at least capable of handling small aircraft from Diego Garcia – and potentially for larger long-distance aircraft from Mauritius given potential constraints of using the US base for international transit.

Any development for resettlement would need activities and livelihoods to provide communities with social focus and sense of purpose, even if payments from the UK to Mauritius under the sovereignty transfer agreement might cover economic costs. Opening formal tourism, commercial fisheries, and ecological conservation activities are amongst the options.

Even without resettlement of a permanent population, partial reopening of commercial fisheries and some extent of formal tourism may be argued for by some stakeholders. The coral reefs and islands are also vulnerable to global climate change impacts, so arguments may also be made for enhanced interventions to support reef resilience and ecosystems’ ability to adapt.

Call to action

The Government of Mauritius has a window of opportunity to establish a state-of-the-art approach to long-term decision-making and management for the islands and coral reef ecosystems of Chagos. An inclusive and environmentally sustainable future will depend on careful and informed decision-making.

Main photo from NASA, Public domain, via Wikimedia Commons

Charles Telfair Centre is an independent nonpartisan not for profit organisation and does not take specific positions. All views, positions, and conclusions expressed in our publications are solely those of the author(s).