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

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 89% of all identified individuals and accounted for 95% of sightings, highlighting these areas are key aggregation sites. This study also reports the 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 important, the implementation of mitigation strategies to reduce fisheries interactions.

A Mozambican marine protected area provides important habitat for vulnerable pelagic sharks.

Pelagic sharks play key roles in marine ecosystems, but are increasingly threatened by human extraction, habitat degradation and mismanagement. We investigated the use of protected and unprotected coastal habitats by bull (Carcharhinus leucas) and oceanic blacktip (Carcharhinus limbatus) sharks in southern Mozambique. Five INNOVASEA VR2W-69 kHz acoustic receivers were positioned in the Bazaruto Archipelago National Park (BANP) as well as one to the south of the park's boundaries. Seven receivers were also deployed 250 km south in the Inhambane estuary and on reef sites off Praia de Tofo. Twelve bull, and six oceanic blacktip sharks, were fitted with INNOVASEA V16 acoustic tags, which generated 933 detections of bull and 12,381 detections of oceanic blacktip sharks over a period of 1391 days. A generalised additive model was used to estimate the effects of seven spatiotemporal and environmental parameters on the frequency of each species' detections. In general, calculated residency indices were highest around the locations monitored in the BANP and one unprotected location off Tofo. Both species were more abundant across the monitored sites, during the summer when water temperatures were ~ 27 °C, when the moon was < 50% illuminated, and when the tide was rising. Detections coincided with each species' reproductive season indicating that both species may be reproductively active in the BANP region. Oceanic blacktip sharks were largely resident and so fisheries management may significantly benefit their population(s) around certain reef habitats in the BANP. The low residency and seasonal detections of bull sharks indicates that they may be transient and so effective conservation may require coordination between regional fisheries managers.