Oct 1, 2020

Study shows Honda Bay important for whale sharks

A whale shark swims in the blue waters of Honda Bay, Philippines. (Photo courtesy of Gonzalo Araujo // LAMAVE)

Whale sharks are known to cross the oceans to feed on a variety of prey, but up until now connectivity within Southeast Asia was limited.

Large Marine Vertebrates (LAMAVE) Research Institute Philippines in a press statement on Tuesday said that they were able to track whale sharks moving between Malaysia, Indonesia, and the Philippines highlighting Honda Bay in Puerto Princesa City as a “globally important site” for the endangered whale sharks.

LAMAVE project leader Ariana Agustines said that Honda Bay’s rich marine biodiversity attracts the second largest whale sharks in the world citing how the bay serves as a “pit stop” for the whale sharks as they make their “international return”.

 

One of the whale sharks fitted with a PAT tag in Honda Bay. (Photo courtesy of Duncan Murrell // LAMAVE)

“Our results reveal Honda Bay as possibly the largest aggregation site for the endangered whale shark in the region. Through employing several data collection methods—satellite telemetry, dedicated surveys and citizen science, we report the movement within national waters as well as the first international return in Asia,” Agustines said.

Agustines and her team identified a total of 117 individual whale sharks by comparing the unique spot pattern on a whale sharks skin—a method known as photo identification. These individuals were identified during dedicated research surveys in Honda Bay, while a further 66 were identified through data mining citizen science reports—usable photos of whale sharks posted by the public on social media platforms.

Research sample showed a 3-meter juvenile male first identified in East Kalimantan, Indonesia in December 2013 which was re-sighted by the research team whilst on a survey in Honda Bay, Philippines in October 2018.

Further photo identification matches confirmed connectivity between Honda Bay and other sites in the Philippines including Tubbataha Reefs Natural Park and Oslob, Cebu.

In addition to photo identification, the research team deployed pop-up archival tags (PAT-tags) to understand regional movements and habitat use. The tags tracked whale sharks movement by recording time, light and depth.

Results from tracks further highlighted Honda Bay as a hub for whale sharks, both within the Philippines and internationally. One whale shark moved from Honda Bay Philippines to Sabah, Malaysia and back to Honda Bay within a year while another tagged shark showed a similar journey returning to Honda Bay after reaching the Malay-Filipino border.

Within the Philippines, tracks showed a whale shark moving northeast of Honda Bay towards Cuyo Island, before returning via Tubbataha Reefs Natural Park.

The connection shown between the neighboring countries prompts the need for cross-boundary collaboration to manage the conservation of this endangered species.

Findings from this study emphasize the need for enhanced management and conservation actions to protect the whale shark through trilateral collaboration.

The field research was partly supported by the Rufford Foundation, Foundation Ensemble, the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) under its International Climate Initiative, the Department of Agriculture-Bureau of Fisheries and Aquatic Resources (DA-BFAR), and the Palawan Council for Sustainable Development (PCSD).

 

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