Seabird researchers working in the Chagos Archipelago should have received a letter from the Prime Minister of Mauritius alerting them to the changed sovereignty of the islands.
This archipelago has so far been administered by the UK as the 'British Indian Ocean Territory'. The International Court of Justice and the UN ruled in 2019 that this administration was unlawful and that Mauritius will henceforth have sovereign rights over the archipelago and its surrounding waters.
If you conduct research in the waters around Chagos, you will therefore now require a permit from Mauritius (or be liable to a fine of up to US$ 800.000 or up to 5 years in jail). Please let me know if you have not received a letter and I can forward you information on whom to contact.