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Master thesis

First ecological, biological and behavioral insights of the ocellated eagle ray Aetobatus ocellatus in French Polynesia

Abstract : Marine species have, for a long time, been considered as less vulnerable to extinction than terrestrial species. Nowadays, they show an extreme sensitivity to global climate changes, with some groups far less resilient than others, as it is the case for the elasmobranchs group. In addition to specific life-history traits (i.e. low fecundity, late maturity, few pups per litter), most of elasmobranchs are pelagic or live in deep waters. Monitoring these species is incredibly difficult and data are missing for almost 50% of them. Elasmobranches need special attention from scientists to improve their conservation at a global scale by increasing knowledge on their biology and their ecology. My EPHE-SVT diploma, done in Moorea with the CRIOBE (USR3278 CNRS EPHE UPVD) aimed to gather the first biological, ecological and behavioral data of the ocellated eagle rays (Aetobatus ocellatus) in French Polynesia. It consisted in three main studies: Study 1/ A genetic study was first done after the discovery of the species complex among the Aetobatus narinari genus. It confirmed the presence of Aetobatus ocellatus in the Society and the Tuamotu archipelagoes. Study 2/ A year of monitoring highlighted the ontogenetic partitioning within the lagoon of Moorea, where the activity turned out to also be different between resting and foraging. This partitioning could allow avoiding intra-specific competition. Study 3/ Known as predator of the pearl oyster, eagle rays have a negative impact on the French Polynesian pearl farms. A study was conducted to determine whether artificial sounds (generated by computer or by boat motor) could ward this species off and be used as a repellent in the pearl farm industry. The boat motor sound was indeed efficient to stop individuals from foraging or to even scare them off. In conclusion, this diploma represents a first sept forward to improve the conservation of Aetobatus ocellatus in a region (i.e.: French Polynesia) where its impacts, both positive for the tourism and negative for the pearl farms, is undeniable.
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Submitted on : Tuesday, January 23, 2018 - 5:47:59 PM
Last modification on : Wednesday, September 28, 2022 - 4:20:11 PM
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  • HAL Id : hal-01690359, version 1



Cecile Berthe. First ecological, biological and behavioral insights of the ocellated eagle ray Aetobatus ocellatus in French Polynesia. Biodiversity and Ecology. 2017. ⟨hal-01690359⟩



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