Intra-species variability in migratory movement of hawksbill turtles in the southwest Indian Ocean

Manon Nivière; Mayeul Dalleau; Jérôme Bourjea; Claire Jean; Stéphane Ciccione; Jeanne A. Mortimer; Vanessa Didon; David Rowat; Gérard Rocamora; Ravaka Ranaivoson; Jamal Mahafina; Lalatiana Odile Randriamiharisoa; Eliott Barichasse; Olivier Bousquet; Anne Barat; Antoine Laforge; Katia Ballorain

doi:10.3354/esr01309

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Endangered Species Research

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ESR 53:379-393 (2024) - DOI: https://doi.org/10.3354/esr01309

Intra-species variability in migratory movement of hawksbill turtles in the southwest Indian Ocean

Manon Nivière^1,*, Mayeul Dalleau^1,2, Jérôme Bourjea³, Claire Jean⁴, Stéphane Ciccione^1,4, Jeanne A. Mortimer^5,6, Vanessa Didon⁷, David Rowat⁷, Gérard Rocamora⁸, Ravaka Ranaivoson⁹, Jamal Mahafina¹⁰, Lalatiana Odile Randriamiharisoa¹¹, Eliott Barichasse¹², Olivier Bousquet^13,14, Anne Barat¹³, Antoine Laforge¹³, Katia Ballorain¹

¹CEDTM, 19 Rue des Frangipaniers, 97424 Piton Saint-Leu, La Réunion, France
²Seanopsis, 97411 Saint-Paul, La Réunion, France
³MARBEC, Université de Montpellier, CNRS, IFREMER, IRD, 34200 Sète, France
⁴Kelonia l’observatoire des tortues marines, 46 rue du Général De Gaulle, 97436 Saint Leu, La Réunion, France
⁵Department of Biology, University of Florida, Gainesville, Florida 32611, USA
⁶Turtle Action Group of Seychelles, PO Box 1443, Victoria, Mahé, Seychelles
⁷MCSS, PO Box 384, Victoria, Mahé, Seychelles
⁸Island Biodiversity & Conservation Centre, University of Seychelles (IBC-UniSey), PO Box 1348, Anse Royale, Mahé, Seychelles
⁹WCS Madagascar, Villa Ifanomezantsoa, Soavimbahoaka, PO Box 8500, Antananarivo 101, Madagascar
¹⁰IH.SM, 2 Rue Dr. Rabesandratana HD, PO Box 141, 601 Toliara, Madagascar
¹¹Madagascar National Parks, Lot AI 10 C Ambatobe, Antananarivo 103, Madagascar
¹²Parc National de Mohéli, Nioumachoi, Ile de Mohéli, Union des Comores
¹³UMR 8105 LACY, Université de La Réunion, CNRS, Météo-France, 15 avenue René Cassin, 97715 Saint-Denis, La Réunion, France
¹⁴Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth 6031, South Africa

*Corresponding author: manon.niviere@gmail.com

ABSTRACT: Implementing effective conservation measures to manage migratory populations is challenging, especially in a relatively inaccessible dynamic environment such as the ocean. With limited financial and human resources, efforts must be intelligently prioritized to achieve conservation success and reduce uncertainties of conservation efforts. The southwest Indian Ocean (SWIO) hosts some of the world’s most important breeding grounds for the Critically Endangered hawksbill turtle Eretmochelys imbricata. However, knowledge gaps remain about the movement patterns of this species. Between 2007 and 2022, we deployed 17 satellite tags onto hawksbill turtles from scattered locations in the SWIO: 16 nesting females—Granitic Islands, Seychelles (n = 9); north Madagascar (n = 5); Moheli, Comoros (n = 1); Juan de Nova, Terres australes et antarctiques françaises (n = 1)—and 1 female bycaught in fisheries (east Madagascar). We found strong variability in migratory movements amongst individuals, particularly in terms of distance and movement persistence. Detailed analysis of movement persistence reveals that these individuals behave differently in neritic and oceanic habitats, with a lower movement persistence in neritic habitats. We identified a total of 12 foraging areas scattered throughout the SWIO, both in coastal and open-sea neritic habitats. These results reinforce the need to consider the importance of neritic habitats, for both migration and foraging, in conservation policies. The quantification of the degree of migratory variability is particularly important to developing conservation plans and strategies at both the national and international level, including the delineation of regional management units (RMUs) in the Indian Ocean.

KEY WORDS: Eretmochelys imbricata · Movement persistence · Migration · Foraging habitat · Southwest Indian Ocean

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Cite this article as: Nivière M, Dalleau M, Bourjea J, Jean C and others (2024) Intra-species variability in migratory movement of hawksbill turtles in the southwest Indian Ocean. Endang Species Res 53:379-393. https://doi.org/10.3354/esr01309

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