thumb|Anchor of the wrecked frigate Utile
Tromelin Island (; , ), once called the Isle of Sand, is a low, flat island in the Indian Ocean about north of Réunion and about east of Madagascar. Both France and Mauritius claim sovereignty over the islands, and France includes it in the Scattered Islands in the Indian Ocean, the fifth district of the French Southern and Antarctic Lands.
Tromelin has facilities for scientific expeditions and a weather station. It is a nesting site for birds and green sea turtles.
Etymology
The island is named in honour of Jacques Marie Boudin de Tromelin de La Nuguy, captain of the French corvette . He arrived at the island on 29 November 1776, and rescued eight stranded enslaved Malagasy people who had been on the island for 15 years.
Description
thumb|upright=1.35|Map of Tromelin Island.
thumb|Present settlement on Tromelin Island.
Tromelin is situated in the Mascarene Basin and is part of the Îles Éparses. It is currently only high. It formed as a volcano, Access by sea is quite difficult as there are no harbours and the only anchorage, to the northwest of the island, is poorly situated.
Fauna and flora
Flora are poorly developed due to weather conditions and lack of fresh water. With the exception of two or three months in summer, this flat island is swept day and night by heavy winds that are sustained in winter. In summer, it can suffer the onslaught of cyclones and tropical storms.
There is only grass and brush (low shrubs) present on the island. Veloutaries (Heliotropium foertherianum) and purslane (Portulaca oleracea), with growth shaped by dominant east winds, are present everywhere on the island.
The fauna consist mainly of hermit crabs (Paguroidea), seabirds, and sea turtles for which the island is an important nesting place. The green turtle (Chelonia mydas) is mainly encountered and, to a lesser extent, the hawksbill sea turtle.
The waters are rich with fish. The French Coral Reef Initiative (IFRECOR) has identified 26 species of corals. Allochthonous species were introduced on the island during the various shipwrecks: rats, mice and rabbits. The latter were decimated in 1986 by cyclone Erinesta.
Important bird area
The island has been identified as an Important Bird Area (IBA) by BirdLife International because of its significance as a seabird breeding site. Both masked (with up to 250 pairs) and red-footed boobies (up to 180 pairs) nest on the island. Sulidae populations have seriously declined in the western Indian Ocean with those on Tromelin among the healthiest remaining.
The island's masked boobies are of the western Indian Ocean subspecies (Sula dactylatra melanops), of which Tromelin is a stronghold. The red-footed boobies constitute the only polymorphic population in the region, indicating its biogeographical isolation. Both great and lesser frigatebirds used to nest on the island. The breeding populations of both birds had been extirpated, though that has changed.
Invasive rats that arrived on Tromelin Island centuries ago with the wreck of a slave ship decimated the island's seabird population. By the time eradication efforts began in 2005, only two booby species remained. Despite the lack of any active restoration actions after the eradication of rats, and the remoteness of the island, 17 years after rat eradication, the seabird community increased from two to seven breeding species, and from 353 to 4758 breeding pairs (total for all species).
Unlike seabirds, there are no resident landbirds on Tromelin Island.
History
thumb|Aerial view
The island was discovered by France in the 1720s. It was recorded by the French navigator Jean Marie Briand de la Feuillée and named Île de Sable ("Isle of Sand").
Wreck of the ship Utile
On 31 July 1761 the French ship Utile ("Useful"), a frigate of the French East India Company, chartered by Jean-Joseph de Laborde and commanded by Captain Jean de La Fargue, transporting slaves from Madagascar to Mauritius in contravention of Mauritian law, ran onto the reefs of the island. The ship had departed Bayonne in France with 142 men. After a stopover on Mauritius (then called the Isle de France), the ship embarked 160 Malagasy men, women, and children at Foulpointe, on the east coast of Madagascar, to bring them into slavery on Mauritius, despite the prohibition of trafficking decreed by the governor. A navigation error, due to the use of two conflicting charts, caused the vessel to wreck on the reefs of Tromelin Island (then called the Isle of Sand). The ship was a frigate, not a slave ship, and thus was not equipped with the shackles and chains usually found on slave ships.
After the wreck, the crew and about 60 Malagasy people managed to reach the island, but the rest of the slaves, locked in the hold, drowned. The crew retrieved various equipment, food and wood from the wreckage. They dug a well, providing drinking water, and fed on salvaged food, turtles, and seabirds.
Castellan left Mauritius (Isle de France) to return to France in 1762 and never gave up hope to one day return to the Isle of Sand to save the Malagasy people. The news of the castaway slaves got published and stirred the Parisian intellectual milieu; later, the episode was all but forgotten with the end of the Seven Years' War and the bankruptcy of the East India Company. Indeed, the treaty does not specifically mention all the dependencies of Mauritius, which leads to uncertainty on the sovereignty of Tromelin, and the official text was that written in French. During the British period of Mauritius, France administered the island as a dependency of the region of Réunion and built infrastructure without British protest. France and Mauritius have been negotiating for years in regard to the possible establishment of a condominium over the island. In 2010, Mauritius and France reached an agreement on the co-management of Tromelin, without prejudice to the sovereignty of Mauritius over Tromelin.
The French claim to sovereignty dates from 29 November 1776, the date that the ship Dauphine arrived.
The Mauritian claim to sovereignty is based on the fact that the island must have been ceded to United Kingdom by the treaty of Paris in 1814 and should not continue to be administered by France as a dependency of Réunion.
The United Nations has never recognized Mauritian sovereignty over Tromelin. In 1954, France constructed a meteorological station and a landing strip on the island.
It is a matter of dispute whether the building agreement transferred sovereignty of Tromelin from one to the other, and Mauritius claims the island as part of its territory, on the grounds that France did not retain its sovereignty over the island in 1814, which was de facto part of the colony of Mauritius at the time of independence. Indeed, as early as 1959, even before independence, Mauritius informed the World Meteorological Organization that it considered Tromelin to be part of its territory. A co-management treaty was reached by France and Mauritius in 2010, but has not been ratified.
The Scattered Islands in the Indian Ocean are partially claimed by the Comoros, Madagascar, and Mauritius. The Malagasy and Mauritian claims, however, are significantly later than their access to independence. However, the agreement reached in October 2024 on the restitution to Mauritius of the Chagos Islands by Great Britain, in the heart of the Indian Ocean, notably home to the American base of Diego Garcia, has relaunched the debate in Madagascar.
Tromelin has an Exclusive Economic Zone (EEZ) of , contiguous with that of Réunion. The island's autonomous weather station, which warns of cyclones, is still operated by France and is supported by personnel from the French Southern and Antarctic Lands (TAAF). Staff are rotated every three months through resupply missions mounted from Réunion.
Climate
Tromelin Island has a tropical savanna climate (Köppen climate classification Aw). The average annual temperature in Tromelin is . The average annual rainfall is with February as the wettest month. The temperatures are highest on average in February, at around , and lowest in August, at around . The highest temperature ever recorded in Tromelin was on 1 January 1983; the coldest temperature ever recorded was on 12 July 1964.