Philippines · Since 2015

Tubbataha Shark Monitoring

Diver surveys and baited cameras recorded about seven sharks and rays per hectare (about three per acre) at Tubbataha, three times the density of reef sharks in the Great Barrier Reef's no-take zones.

Led by LAMAVE, with MMF

About 7sharks and rays per hectare (about 3 per acre), almost all reef sharks

3×the reef shark density of the Great Barrier Reef's no-take zones

113baited camera drops in 2015 and 2016

92%of camera drops recorded at least one shark or ray

Tubbataha Reefs Natural Park, isolated far out in the Sulu Sea, has been closed to all fishing since 1988. Working with LAMAVE (Large Marine Vertebrates Research Institute Philippines) and the Tubbataha Management Office, we helped conduct the park’s first comprehensive survey of its sharks and rays.

The park lies about 170 km (110 miles) southeast of Puerto Princesa, Palawan, in the Philippines, and encompasses the North and South Atolls and Jessie Beazley Reef. The no-take park covers about 1,000 km² (390 square miles) and became a UNESCO World Heritage Site in 1993. The survey was led by Ryan Murray of LAMAVE, who lived for months at the park’s ranger station, with the Tubbataha Management Office, including protected area superintendent Angelique Songco and Segundo Conales Jr. MMF’s Dr. Simon Pierce helped collect the field data and co-authored the study, published in the Journal of Asia-Pacific Biodiversity in 2018. The Global FinPrint project, a worldwide survey of reef sharks and rays, partly funded the work.

What the project has done

Helped LAMAVE survey the park’s sharks and rays in 2015 and 2016 with 20 diver surveys and 113 drops of baited remote underwater video cameras.
The survey recorded 8 species on the diver surveys and 14 on the cameras, establishing a baseline for 15 species of sharks and rays in the park.
Co-authored the park’s first comprehensive assessment of its sharks and rays, published in 2018.

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Survey findings

Diver surveys and baited cameras

Divers counted sharks and rays on 10 surveys in May 2015 and 10 in June 2016, recording 309 encounters with 8 species. Baited cameras deployed between March and June in both years recorded 14 species, with at least one shark or ray appearing in 92% of the 113 deployments. The cameras logged an average of 2.09 sharks and rays per hour of footage, a standard index of relative abundance, and neither survey method detected a significant difference in reef shark numbers between the two years.

A reef shark swims over the reef beneath a school of fusiliers at Tubbataha Reefs, Philippines

Reef shark density

Reef sharks accounted for 95.8% of the divers’ encounters. Overall density was about 7 sharks and rays per hectare (about 3 per acre). Whitetip reef sharks (Triaenodon obesus) reached 3.72 per hectare and gray reef sharks (Carcharhinus amblyrhynchos) 3.16 per hectare (1.51 and 1.28 per acre, respectively). Reef shark density was three times that recorded in the Great Barrier Reef’s no-take zones, where all fishing is banned, and about twice that at the Cocos (Keeling) Islands. On the baited cameras, reef shark abundance was about three and seven times higher than in two no-take zones in Raja Ampat, Indonesia, and about 2.5 times higher than in Fiji’s Namena Reserve.

A whitetip reef shark rests under a ledge at Tubbataha Reefs, Philippines

Other sharks and rays

The cameras also recorded tiger sharks, scalloped hammerheads, thresher sharks, silky sharks, silvertip sharks, whale sharks, and manta rays. Our work with LAMAVE has also tracked young whale sharks tagged at Tubbataha, and 32 reef manta rays identified at Tubbataha and Cagayancillo were included in a national manta ray study.

A barrel sponge and feather stars on the reef at Tubbataha, with a whale shark passing behind

Factors behind the high shark density

The study points to four factors: the park’s large size; strict enforcement, with ranger patrols and radar; its isolation; and its age. The authors note that reef sharks take 7 to 10 years to mature, so protection since 1988 has covered at least two full generations. The park’s rangers are drawn from the Tubbataha Management Office, the Philippine Coast Guard, the Philippine Navy, and the municipality of Cagayancillo.

A reef shark swims in open water off the reef at Tubbataha, Philippines

Study recommendations

Agencies creating large no-take marine protected areas should adopt management and zoning like Tubbataha’s, and use its shark populations as a baseline to measure recovery elsewhere.
Continue diver and camera surveys in the park to monitor long-term trends.
Use tracking tags to test how well the park’s boundaries protect its sharks.