Distribution of the reef manta ray Mobula alfredi and the oceanic manta ray Mobula birostris in the Philippines: A collaborative effort for conservation

Abstract

Little is known about manta ray population size, structure, and connectivity in the Philippines. In collaboration with dive operators, non-governmental organizations, and authorities, sightings of manta rays were collated into a single national database. Using in-water photographs and videos gathered through citizen science and dedicated research efforts, this study compiled sightings between 2004 and 2020, showing 22 separate sites throughout the archipelago with manta rays present. A total of 392 individual reef manta rays (Mobula alfredi) and 107 oceanic manta rays (Mobula birostris) were identified from the collected footage. Four specific sites in the provinces of Masbate and Palawan together hosted 87% of all identified individuals and accounted for 94% of sightings, highlighting these areas are key aggregation sites. This study also reports movements of M. birostris within the Philippines, based on photo-identification of three individuals moving 150 km between Cebu and Masbate. Despite the growing number of recreational divers in Daanbantayan and San Jacinto, an 80% decline in M. birostris sightings was observed at these sites. To ensure effective future conservation, it is recommended that efforts focus on the identification and protection of manta ray hotspots and migratory corridors, the creation of a sustainable tourism framework, and most importantly, on the implementation of mitigation strategies to reduce fisheries interactions.