Satellite tag study reveals Philippine waters are incredibly important for endangered whale sharks
Whale sharks moved between the Sulu and Bohol Seas, and the Pacific Ocean
Bohol Sea, Philippines, July 24 2018, a new scientific study by Large Marine Vertebrates Research Institute Philippines (LAMAVE), Marine Megafauna Foundation (MMF) and Tubbataha Management Office (TMO) on satellite tracking juvenile whale sharks in the Philippines has been published in the journal Peer J. To date, it is the most complete tracking study of whale sharks in the country, with satellite tags deployed on different individuals in multiple sites.
The Philippines is an important hotspot for whale sharks and globally hosts the third largest known population of whale sharks (www.whaleshark.org). While the species has been protected in the Philippines since 1998, globally the species was uplisted in 2016 to ‘endangered to extinction’ in the IUCN Red List of Threatened Species due to a population decline of more than 50%, largely caused by continued exploitation in the Indo-Pacific. Particularly in South East Asia, concerns remain due to continued fishing in regional waters; understanding the movements of whale sharks in the Philippines is vital if we are to identify conservation priorities for the species.
In this study, 17 individual whale sharks were tagged with Wildlife Computers SPOT5 satellite tags in three different locations in the Philippines: Panaon Island (Southern Leyte), northern Mindanao (Misamis Oriental and Surigao del Norte) and Tubbataha Reefs Natural Park (Palawan). Tagging took place between April 2015 and April 2016. All tagged whale sharks were juveniles, ranging in size between 4.5 – 7 meters and 73% of them were male.
By attaching SPOT5 satellite tags to the sharks, the team was able to follow the movements of juvenile whale sharks in near real-time. The tags work by communicating with passing ARGOS satellites, transmitting a location when the wet/dry sensor is triggered when a tagged whale shark breaks the surface. To aid transmission tags were tethered to a whale shark by a 1.8-meter line to ensure the tags broke the surface more frequently.
Tracks from the tags revealed that all whale sharks stayed within the Philippines over the tracking period, emphasising the importance of the archipelago for the species. The longest track observed was from a whale shark originally tagged in Tubbataha Reefs Natural Park, which appeared to swim through the Sulu and Bohol Seas and into the Pacific, a journey accumulating over 2,500 km in length. While whale sharks are not known for their speed, results revealed that one individual whale shark was averaging 47km a day, further emphasising the species’ mobile tendencies.
Dedicated research by LAMAVE and citizen science has identified over 600 individuals in the Sulu and Bohol Seas, yet the proximity of this population to fisheries in the broader region (South China Sea) means it is vital to monitor this population as a whole to understand if this population is in recovery or continuing to decline. Identifying threats and mitigation strategies is a conservation priority for the species.
LAMAVE continues to study whale sharks in five key areas in the Philippines, working with local and national governments as well as collaborating organisations to develop conservation strategies for this iconic species.
Notes to the Editor
Large Marine Vertebrates Research Institute Philippines (LAMAVE) is the largest independent non-profit non-governmental organization solely dedicated to the conservation of marine megafauna and their habitats in the Philippines. LAMAVE strives for conservation through scientific research, policy and education. www.lamave.org
Tubbataha Reefs Natural Park is the largest marine protected area in the Philippines. It was declared a UNESCO World Heritage Site in 1993. The park is managed and protected by the Tubbataha Protected Area Management Board, the Tubbataha Management Office and the Marine Park Rangers. www.tubbatahareefs.org
The Marine Megafauna Foundation was created in 2009 to research, protect and conserve the populations of threatened marine megafauna around the world. ‘Megafauna’ are large marine species such as sharks, rays, marine mammals and sea turtles. www.marinemegafauna.org
The study can be viewed here and should be cited as follows: Araujo et al. (2018), Satellite tracking of juvenile whale sharks in the Sulu and Bohol Seas, Philippines. PeerJ 6:e5231; DOI 10.7717/peerj.5231
A copy of this press release is available for download HERE.
If you would like more information about this topic, please contact Sally Snow at s.snow[at]lamave.org. Photos and video are available upon request.