In our study, the habitat for sperm whales extended over a restricted latitudinal band (19.5-22°S), which contrasts with previous studies showing north-south migrations (Whitehead et al. 2008, Findlay & Best 2016). During the dry season, the predicted distribution was limited to coastal waters of Mauritius and Reunion islands, reinforcing the need to implement conservation measures in these areas, i.e. promote reserve designation, extend the actual MPAs. Currently, Mauritius has eight MPAs including two marine parks and six areas declared as fishing reserves. They are however relatively small (between 3.5-63.4 km²) and confined close to shore (Francis et al. 2002). Data on animal distribution is often lacking when designing MPAs, and findings like ours are therefore essential to support conservation planning. Our results could also contribute to the regulation of the whale watching industry, which is omnipresent in such touristic areas. Restricting disturbance of animals is of particular importance at breeding sites like Mauritius coastal waters. Rather than static and sometimes inadequate MPAs, here we recommend designing dynamic MPAs based on the seasonal prediction maps of the whales (Maxwell et al. 2015). In addition to filling a gap in our knowledge about the movements and habitats of sperm whales in the South Western Indian Ocean, our study will contribute to the implementation of conservation measures in the waters of Mauritius and Reunion by clearly delineating the breeding and foraging grounds of this vulnerable species.
Data Accessibility Statement. Data available from the Dryad Digital Repository:https://doi.org/10.5061/dryad.bnzs7h482.
Competing interest. None declared.
Author Contributions. PC performed the data analysis and wrote the manuscript. MV, SF, DJ and MPHJ designed the experiment, collected the data and supervised the analysis. MV, SF, DJ and MPHJ participated in the field effort. PC, MV, SF, DJ and MPHJ assisted with organizing the data and analysis and interpretation of the results. All the authors shared the responsibility for contributing to the final version of the manuscript.
Funding information. The study was financed by EXAGONE Réseau TERIA who funded the field campaigns logistics, the tags and the expertise cost for the data analysis.
Acknowledgements. The authors would like to thank the Mauritian authorities who allowed us to implement the Maubydick project during three field campaigns in 2014, 2016 and 2019 and issued permits. A special thanks to Dr M. Rezah Badal and Dr Beenesh Anand Motah, Directors of the Hydrocarbon/Mineral Production Unit Department for Continental Shelf, Maritime Zones Administration & Exploration, Ministry of Defense and Rodrigues. We are also grateful to the Ministry of Ocean Economy, Marine Resources, Fisheries and Shipping and especially Dr Khadun, acting as the permanent secretary for providing on board officers of the Fisheries division as well as the Commanding officer of the National Coast Guard. We are also very grateful to our friend Hugues Vitry, chairman of the Mauritius Marine Conservation Organization (M2C0), well known as the man who speaks to Sperm whales, NGO implementing the Maubydick project for its kind and continuous support and advices, for his strong affinity and knowledge about the marine megafauna, and for his active participation to the first field mission in 2014. We also thank the M2CO team and specially Alex Preud’Homm and François Sarano for providing precious information on the photo ID and sexes of the sperm whales individuals we encountered and tagged. We also thank the team of the blue water diving centre and especially the skipper Navin. We are also very grateful to our friends Jean Noel Mamet and Alain Dubois from the DOLSWIM Company as well as all the skippers and team involved, who provided the tagging boat and the skippers at the minimum cost during the three field missions and their valuable field advices. We wish to thank the company EXAGONE Réseau TERIA for the main funding of the field campaigns, the data analysis and the preparation of that current publication, and Mikkel Villum Jensen who did the tagging and prepared the tags and attachments.