Satellite tracking of juvenile whale sharks in the Sulu and Bohol Seas, Philippines

The whale shark Rhincodon typus was uplisted to ‘Endangered’ in the 2016 IUCN Red List due to >50% population decline, largely caused by continued exploitation in the Indo-Pacific. Though the Philippines protected the whale shark in 1998, concerns remain due to continued take in regional waters. In light of this, understanding the movements of whale sharks in the Philippines, one of the most important hotspots for the species, is vital. We tagged 17 juvenile whale sharks with towed SPOT5 tags from three general areas in the Sulu and Bohol Seas: Panaon Island in Southern Leyte, northern Mindanao, and Tubbataha Reefs Natural Park (TRNP). The sharks all remained in Philippine waters for the duration of tracking (6–126 days, mean 64). Individuals travelled 86–2,580 km (mean 887 km) at a mean horizontal speed of 15.5 ± 13.0 SD km day−1. Whale sharks tagged in Panaon Island and Mindanao remained close to shore but still spent significant time off the shelf (>200 m). Sharks tagged at TRNP spent most of their time offshore in the Sulu Sea. Three of twelve whale sharks tagged in the Bohol Sea moved through to the Sulu Sea, whilst two others moved east through the Surigao Strait to the eastern coast of Leyte. One individual tagged at TRNP moved to northern Palawan, and subsequently to the eastern coast of Mindanao in the Pacific Ocean. Based on inferred relationships with temperature histograms, whale sharks performed most deep dives (>200 m) during the night, in contrast to results from whale sharks elsewhere. While all sharks stayed in national waters, our results highlight the high mobility of juvenile whale sharks and demonstrate their connectivity across the Sulu and Bohol Seas, highlighting the importance of the area for this endangered species

Tubbataha Reefs Natural Park: the first comprehensive elasmobranch assessment reveals global hotspot for reef sharks

Elasmobranchs are experiencing population declines worldwide because of anthropogenic stressors. Marine protected areas (MPAs) have been shown to benefit mesopredatory species of shark. The Tubbataha Reefs Natural Park (TRNP) is a United Nations Educational, Scientific and Cultural Organization World Heritage Site and the largest no-take MPA in the Philippines, yet information on the current status of elasmobranchs in the park is limited. Here, we investigate the abundance and biodiversity of elasmobranchs in TRNP using underwater visual census (UVC) and baited remote underwater video (BRUV) surveys. Twenty UVC were conducted in May 2015 (n = 10) and June 2016 (n = 10), documenting eight species of elasmobranchs with an average density of 7.18 sharks ha-1 for both years. A total of 113 successful BRUV surveys were conducted in TRNP between March–June 2015 (n = 47) and April–June 2016 (n = 66). The BRUV surveys recorded 14 species with an average catch per unit effort of 2.09 elasmobranchs per hour for both years. Both survey methods report some of the highest densities of the grey reef shark Carcharhinus amblyrhynchos and the whitetip reef shark Triaenodon obesus documented worldwide. This study underlines the importance of large, well-managed MPAs such as TRNP for the conservation of reef-associated elasmobranchs. Keywords: Baited remote underwater video, Elasmobranch conservation, Marine protected area, Reef sharks, Southeast Asi

Distribution of the reef manta ray <i>Mobula alfredi</i> and the oceanic manta ray <i>Mobula birostris</i> in the Philippines: a collaborative effort for conservation

From Crossref journal articles via Jisc Publications RouterHistory: epub 2022-12-19, issued 2022-12-19Article version: VoRPublication status: PublishedFunder: Rufford Foundation; FundRef: 10.13039/100007463Funder: Save Our Seas Foundation; FundRef: 10.13039/50110000766

Distribution of the reef manta ray <i>Mobula alfredi</i> and the oceanic manta ray <i>Mobula birostris</i> in the Philippines: A collaborative effort for conservation

From Crossref journal articles via Jisc Publications RouterHistory: epub 2022-11-30, issued 2022-11-30Article version: VoRPublication status: Publishe