The small, isolated, inhospitable (and inhabited) island of Tromelin, located in the Indian Ocean north of Mauritius and the French Reunion island, and east of Madagascar (see map), has been the subject of passionate debate in recent weeks in France, both in the media (here and here) and within the Parliament (transcript of the debate before the French National Assembly).
Tromelin is a flat and small feature, about 1,700 metres long and 700 metres wide, with an area of about 80 hectares (200 acres). Its flora is limited, while the site is known to host significant numbers of seabirds. There is no harbour nor anchorages on the island, but a 1,200-metre airstrip, and there appears to be no continuous human presence.
Tromelin was discovered by a French navigator in 1722, and France today claims sovereignty over it by virtue of historical title (discovery of terra nullius) dating back to that date. The islet was the scene of a sad – and little known – episode of history as the place where approximately 60 Malagasy men and women were abandoned for 15 years in the 18th century after a French ship transporting slaves eschewed on the island. Most of the slaves died within a few months. The survivors were finally rescued in 1776, when Bernard Boudin de Tromelin, captain of the French warship La Dauphine, visited the island and discovered seven women and an eight-month-old child. Captain Tromelin also raised a French flag on the island – and his name was given to it.
French possession of Tromelin was interrupted by Britain which took control of the island in 1810. Then in 1954, the British gave their consent to France’s effective control over Tromelin. But sovereignty over Tromelin is still disputed, and the island has been claimed by the newly independent Mauritius since 1976, and reportedly also by Madagascar and the Seychelles (see V. Prescott, ‘Indian Ocean Boundaries’ at 3462-63). The controversy in France over Tromelin has led to the postponing of the ratification by the Parliament of a framework agreement entered into by France and Mauritius in June 2010, providing for joint economic, scientific and environmental management (cogestion) of the island and of surrounding maritime areas.
Concerns expressed in France revolve around the issue of a possible loss or abandonment by France of its sovereignty over the feature, and most of all of its rights over the exclusive economic zone (EEZ) of Tromelin, that France established in 1976 (see Decree no. 78-146 of 3 February 1978, establishing, pursuant to the Act of 16 July 1976, an economic zone off the coasts of the islands of Tromelin, Glorieuses, Juan de Nova, Europa and Bassas da India, Law of the Sea Bulletin, No. 71  at 16). Critics also point to the risk of creating a precedent that could be used to fuel arguments of those countries (Mauritius, the Comoros and Madagascar) which repeatedly dispute French claims of sovereignty over the other French-occupied Scattered Islands (Îles Éparses) of the Indian Ocean (Juan de Nova, Glorioso and Europa islands, the Bassas da India atoll, and the feature known as Banc du Geyser), and related maritime zones. For example, Section 111 of the Constitution of Mauritius provides that Tromelin is part of Mauritian territory. Mauritius also deposited with the UN Department for Ocean Affairs and the Law of the Sea, pursuant to Articles 16 and 47 of UNCLOS, charts and lists of geographical coordinates of basepoints and baselines for the maritime zones of Mauritius, which include basepoints around Tromelin (see Maritime Zone Notification M.Z.N.63.2008.LOS of 27 June 2008).
The issue of sovereignty over Tromelin is a very complex one, that should be further examined through interpretation of relevant international agreements, including the Treaty of Paris of 30 May 1814 between France and the United Kingdom – which transferred sovereignty over the French colony of Mauritius (then known as Isle of France) and its dependencies to the British –, and assessment of the subsequent practice of the States concerned. For the record, the provision concerning Mauritius (then Isle of France) in the Treaty of Paris was its Article VIII, worded as follows:
His Britannic majesty stipulating for himself and his allies, engages to restore to his most Christian majesty [French King Louis XVIII], within the term which shall be hereafter fixed, the colonies, fisheries, factories, and establishments of every kind, which were possessed by France on the 1st of January 1792, in the seas and on the continents of America, Africa, and Asia, with the exception however of the islands of Tobago and St. Lucie, and of the Isle of France and its dependencies, especially Rodrigues and Les Sechelles, which several colonies and possessions his most Christian majesty cedes in full right and sovereignty to his Britannic majesty, and also the portion of St. Domingo ceded to France by the treaty of Basle, and which his most Christian majesty restores in full right and sovereignty to his Catholic majesty » (full text of the Treaty in E. Hertslet, The Map of Europe by Treaty, at 1 – emphasis added).
Assessing the merits of claims regarding Tromelin would by far exceed the limits of this note. The exercise will likely include an in-depth examination of relevant archival materials, namely those found in the Bibliothèque Nationale de France (the National Library of France) and the Archives Nationales d’Outre-Mer (the National Overseas Archives), as well as in the British archives including those of the United Kingdom Hydrographic Office. At first sight, the validity of the claims of France regarding Tromelin is not obvious and needs to be critically assessed under the international law relating to the acquisition of territory.
Mauritius is of the view that the assignment by the Treaty of Paris of the Isle of France (Mauritius) to the British Crown included Tromelin, so that upon reaching independence in 1968, Mauritius should have entered into possession of Tromelin. France of course holds a contrary view. A French Parliament report advocating the ratification of the 2010 framework agreement between France and Mauritius referred to the multiplicity of France’s “acts of sovereignty and administration over this islet (îlot) even before the independence of Mauritius [in 1968] […] without UK protest”. Basically, France’s historical title to the island is to be assessed against other claims formulated by Mauritius, and reportedly also by Madagascar and the Seychelles.
Irrespective of the sovereignty over Tromelin, it is far from certain, at first sight, that this island (or islet) of Tromelin be entitled to full maritime zones and in particular an exclusive economic zone (EEZ). This is dependent in particular on interpretation of the terms of Article 121 para. 3 of UNCLOS, according to which “[r]ocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone or continental shelf”. The precise meaning of Article 121 para. 3 has long proven controversial (see e.g. Erik Franckx, ‘The Regime of Islands and Rocks’, in D.J. Attard, M. Fitzmaurice, N.A. Martínez Gutiérrez (eds.), The IMLI Manual on International Maritime Law, Vol. I, Law of the Sea, at 99-124.).
Interpretation of this article has been one of the main points addressed by the Arbitral tribunal in its Award of 12 July 2016 in the South China Sea Arbitration (Republic of the Philippines v. People’s Republic of China) case before the PCA. The tribunal in that case engaged in a thorough interpretation exercise and made a number of findings as to the accurate meaning of all components of paragraph 3 (« rocks », « cannot » « sustain », « human habitation », « or », and « economic life of their own »), which will probably offer some valuable guidance regarding future similar cases. What should be assessed properly is whether Tromelin, due to its physical and geographical characteristics (as evidenced by precise and recent scientific works and reports), is entitled – as any island – to full maritime zones under Article 121 para. 2 of UNCLOS, or if it meets the definition of a rock within the meaning of Article 121 para. 3, in which case it would not generate an exclusive economic zone or a continental shelf.
As regards prospects for a settlement of the issue of Tromelin (and possibly other Îles Éparses), several observations may be made. First, while it has been reported that Mauritius would be prepared to submit the dispute to the ICJ, the jurisdictional basis for such referral remains unclear. One has to bear in mind that France, upon ratifying UNCLOS in 1996, has declared that it does not accept any of the dispute settlement procedures provided for in Part XV, section 2, of UNCLOS with respect inter alia to “[d]isputes concerning the interpretation or application of articles 15, 74 and 83 relating to sea boundary delimitations, or those involving historic bays or titles”. Second, the settlement of the sovereignty issue may possibly be disjoined from the issue of maritime entitlements, as the Arbitral tribunal did in the South China Sea Arbitration case when it pronounced on maritime entitlements of various features of the South China sea without addressing the sovereignty issue over those features. As various commentators have stressed, the tribunal could hardly have done otherwise, since UNCLOS is not concerned with sovereignty over land territory and islands, and assumes for the purposes of delimitation that the issue of sovereignty is resolved. This was also the position of the Arbitral Tribunal in the Chagos Marine Protected Area Arbitration (Mauritius v. United Kingdom) case, where Mauritius opposed the establishment by the UK of a marine protected area around the Chagos archipelago, administered by the UK but claimed by Mauritius. In its Award of 18 March 2015, the Tribunal held in substance that Mauritius’ claim that the UK did not qualify as a “coastal state” within the meaning of UNCLOS as regards the Chagos Islands concerned in fact the question of sovereignty over the Chagos, which was not a matter concerning the interpretation or application of UNCLOS, and therefore that it did not have jurisdiction.
This separation between sovereignty over Tromelin and the determination of maritime zones generated by the latter appears, even if implicitly, as the path chosen by the negotiators of the 2010 framework agreement between France and Mauritius. While disagreeing on the issue of sovereignty, the two sides agreed on Tromelin’s entitlement to an EEZ. The French side, while reaffirming its sovereignty over Tromelin – and that it would not give its consent to any third-party dispute settlement mechanism on that issue –, stated that the objective of the agreement is “basically political and aims at overpassing the sovereignty dispute […] through adoption of a partnership approach in three specific sectors: environment, archeology and fisheries” (see Report of the French Senate). It should also be noted that France and Mauritius had also adopted a pragmatic approach in 1980 when they reached agreement on the delimitation of part of their maritime boundary – setting Tromelin aside (see Convention between the Government of the French Republic and the Government of Mauritius on the delimitation of the French and Mauritian economic zones between the islands of Reunion and Mauritius, 2 April 1980, reprinted in US Department of State, Office of the Geographer, Maritime Boundary: France (Reunion)-Mauritius, Limits in the Seas No. 95  with map). The above-mentioned report of the French Senate stressed the common view of France and Mauritius on the need to assert control over maritime zones surrounding Tromelin – pending the resolution of the sovereignty dispute –, as a means to establish other marine protected areas, to implement joint policies regarding sustainable fisheries, or to combat illicit dumping, among other issues.
It should also be noted that, given its geographical situation, the determination of the status of Tromelin as regards Article 121 para. 3 of UNCLOS would necessarily impact the localisation of maritime boundaries with certain third States, namely neighbouring islands, especially Madagascar. Clive Schofield recently observed that “the potential maritime claims to be made from the disputed islands of the South China Sea, often illustrated by reference to maps giving these features full-effect in the generation of strict equidistance lines, is misleading” (C. Schofield, ‘What’s at stake in the South China Sea? Geographical and geopolitical considerations’, in R. Beckman, I. Townsend-Gault, C. Schofield, T. Davenport and L. Bernard (eds.), Beyond Territorial Disputes in the South China Sea: Legal Frameworks for the Joint Development of Hydrocarbon Resources at 24).
The author of the present note is of the view that the same observation may be made as regards a number of disputed features of the Indian Ocean – including Tromelin.