Connectivity of the Loggerhead turtle in the Western Indian Ocean

The Loggerhead turtle (Caretta caretta) is one of the seven species of marine turtle in the world. It occurs in the territorial waters of Reunion and Mayotte islands. It is listed in Appendix I of the Washington Convention (CITES) and in the IUCN Red List of Threatened SpeciesTM. More than other species, the Loggerhead is known to interact with fisheries and is susceptible to ingestion of plastic debris and boat strikes. A regional convention for the management and conservation of sea turtles and their habitats in the Indian Ocean and South-East Asia (IOSEA) was established in 2003 under the aegis of the Convention for Migratory Species (CMS). 

Turtle release Photo: Jerome Bourjea

According to Stéphane Ciccione, Director of Kelonia – the observatory of sea turtle in Reunion Island, “Mitigation measures to reduce the impact of anthropogenic threats on marine turtles have recently been implemented in Reunion, but clearly these were insufficient and needed to be further developed, amplified and extended to Mayotte, and more generally in all the Western Indian Region which also hosts important loggerhead populations”.

The measures should be based on clear understanding of the biology of the migratory species, whose habitats are largely scattered in the Indian Ocean region. The objective of this BEST 2012 project COCA LOCA is to increase knowledge on this sea turtle species which so far has been little studied in the Indian Ocean. In particular, explains Jérôme Bourjea in charge of the Marine Turtle Programme at Ifremer “Recent results seem to indicate that the turtles by-caught in the southwestern Indian Ocean may originate from the northwestern Indian Ocean, as well as from the southwestern. Therefore, studying the oceanic migration pathways and the connectivity between populations of the main known breeding sites in the western Indian Ocean (e.g. in Oman, South Africa and south Madagascar) is needed to implement effective management measures at the local level”.

The clear objectives of the project are to:

  • Assess the relative importance of major anthropogenic threats to the Loggerhead turtle in the territorial waters of Reunion;
  • Study the oceanic movements of Loggerhead turtles in the territorial waters of Reunion and Mayotte using satellites, genetic, isotopes and modeling technologies;
  • Establish cooperation between Reunion, Mayotte and the countries hosting nesting sites of this species;
  • Exchange good practices, experiences and scientific knowledge with other teams working on this species in the Atlantic: Azores, Madeira, Canary Islands.

Such regional project will be led by Kélonia in close cooperation with Ifremer and CLS which already have long experience on marine turtle in this region of the world. The three partners are convinced that the implementation of efficient management measures can only be done in the framework of a regional approach in cooperation with all countries concerned. That’s why, says Stéphane, “This project can be a success only if it is done in close relation with local fishermen and our scientific colleagues from Oman, Madagascar and South Africa”.

Jérôme concludes “We hope that this project is just the beginning of a global project aiming to assess global interaction of marine turtle with fisheries – one of the most important threats to these species around the world.”

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