Passions and Obsessions

Study tags manta rays in the Philippines—but confirms they’re in danger

Three of the four hotspots are in the waters of Palawan

LAMAVE researcher studying manta ray in San Jacinto, Ticao-Burias Pass Protected Seascape (Photo by Olivia Johnson/LAMAVE)

A new collaborative scientific study led by the Large Marine Vertebrates Research Institute Philippines (LAMAVE), and in cooperation with partners and the public, has compiled a national population database for manta rays and has identified four hotspots for the species in the Philippines.

The study counts several international and Philippine-based partners; among the latter are the Ticao-Burias Pass Protected Seascape, Department of Environment and Natural Resources V, Provincial Environment and Natural Resources Office; the Tubbataha Management Office; World Wildlife Fund Philippines; Bureau of Fisheries and Aquatic Resources – Region 5, Department of Agriculture; Dive Sibaltan; Ticao Island Resort; and the Marine Wildlife Watch of the Philippines.

The study reports the presence of both reef mantas (Mobula alfredi) and oceanic mantas (Mobula birostris) in the country. A total of 2,659 manta ray sightings were analyzed by the team, and 499 individual manta rays identified using photo-identification methods, which use the unique spot pattern on the ventral side (belly) of the manta ray. These individuals were encountered in 22 different sites across the Philippines, 11 of which both reef manta and oceanic mantas were observed.

Of these 22 sites, the study identified four hotspots where manta rays aggregate: Tubbataha Reefs Natural Park in Cagayancillo, San Jacinto in the Ticao-Burias Pass Protected Seascape, Puerto Princesa City, and Taytay in Palawan. Three of these hotspots are in the waters of Palawan. These four sites accounted for 89 percent of all the individual manta rays, and specific behaviors were observed including cleaning, courtship and feeding.

 “Ticao Pass is one of the Bicol Region’s marine key biodiversity areas known to be home of filter-feeding megafauna like whale sharks, megamouth sharks and mobulas,” says Nonie P. Enolva, senior Fishing Regulations officer/chief, Fisheries Resource Management Section, Bureau of Fisheries and Aquatic Resources – Region 5. “The preponderance of visits of these megafaunas is attributed to how rich the Ticao Pass is in terms of the primary food source that has been provided for them. Thus, the protection of this important fishing ground would also mean the protection of the many marine species that are dependent on it.”

Oceanic Mantas accounted for 107 individuals in the national catalog and resights of this species gave an insight into their movements. One female manta first sighted in Daanbantayan, Cebu, in 2009, became the first recorded movement of an oceanic manta between sites in the Philippines when she was resighted in San Jacinto in 2014 and then back again in Daanbantayan in 2017. Another individual made a similar journey in 2017, covering about150 km (straight-line movement) in five days.

The study highlights key threats continuing to face these species. A quarter of the animals identified in San Jacinto and Taytay showed fishery-related injuries, in the form of damaged or missing fins or severe cuts. Damage to cleaning stations is a further concern; the cleaning sites in San Jacinto have an abundance of fishing gear entangled in the reef, resulting in the damage or destruction of this sensitive habitat.

Sightings of oceanic manta rays (M. birostris) in Daanbantayan, Cebu, dropped from 73 sightings between 2006 and 2012 to only 16 sightings between 2013 and 2019 despite the increased diving in the area. San Jacinto showed a similar trend, from 15 sightings between 2013 and 2014 to only three between 2017 and 2019—an alarming 80 percent decline in sighting frequency that may be attributed to fishing activities in part of its assumed range.

Conservation strategies such as marine protected areas and fishing gear regulations should be urgently adopted in these sensitive sites, especially in the identified hotspots which do not benefit from species-specific protection, such as Taytay and Puerto Princesa City.

A reef manta ray in Tubbataha Reefs Natural Park, Cagayancillo, Palawan (Photo by Ryan Murray/LAMAVE)

Large Marine Vertebrates Research Institute Philippines (LAMAVE) is an independent non-profit non-government organization dedicated to the conservation of marine megafauna and their habitats in the Philippines. LAMAVE strives for conservation through scientific research, policy and education. For more information visit: | Facebook | Instagram | Twitter.

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