Philippines: using citizen science and dedicated research to understand a global hotspot for the world's largest fish

The whale shark Rhincodon typus is the world’s largest fish inhabiting tropical and warm temperate waters. The species is Endangered due to continued exploitation primarily in the Indo-Pacific region for their meat, oil and... [ view full abstract ]

The whale shark Rhincodon typus is the world’s largest fish inhabiting tropical and warm temperate waters. The species is Endangered due to continued exploitation primarily in the Indo-Pacific region for their meat, oil and fins. The Philippines was once home to one of the largest targeted fisheries for the species, with >100 whale sharks landed seasonally in the Bohol Sea alone. Following a national ban in 1998, tourism with the species developed in the town of Donsol in Luzon, which still supports local livelihoods. Tourism further developed in Pintuyan, Southern Leyte, where whale sharks aggregate seasonally between November-June. An unregulated tourism industry also developed in Oslob, Cebu, where whale sharks are provisioned daily, year-round. A smaller operation also operates out of Puerto Princesa in Palawan, and encounters with whale sharks are substantial at Tubbataha Reefs Natural Park in the Sulu Sea during the tourist season between March-July. By photographing their unique spot pattern, whale sharks can be individually identified through photo-ID. Using this technique, and by harnessing the widespread boom of tourism in the Philippines, we have now identified 1251 individuals across multiple provinces. We receive year-round reports from citizen scientists from across the Philippines, highlighting whale sharks’ highly mobile nature and widespread distribution. This also highlights that although aggregation hotspots are management priorities, migratory corridors and other areas of importance are widespread and difficult to manage. Citizen science is an invaluable tool for whale shark conservation and can provide cost-effective monitoring of the species and its habitats.