The importance of shark-infested waters
Dr Simon J Pierce is a marine conservation biologist and underwater photographer from New Zealand. He is a co-founder and Principal Scientist at the Marine Megafauna Foundation, where he leads the global whale shark research programme, and a regional Co-Chair for the IUCN Shark Specialist Group.
There are 905,000 results on Google for “shark-infested waters”.
That isn’t just an indictment of lazy writing. It’s genuine fake news. Fact is, a quarter of all shark species are threatened with global extinction. As a vital component of healthy marine ecosystems, we need a lot more sharks than we’ve got.
That makes it important to recognise and learn from real marine conservation success stories. It takes a lot of work, and long-term commitment, but the ocean can be protected and restored.
A new paper, led by the Large Marine Vertebrates Research Institute Philippines (LAMAVE), with help from the Tubbataha Management Office and myself, has showcased the benefits to sharks that can be achieved by effective marine protected areas (MPAs).
Around 200 species of the world’s 1,148 shark and ray species live in the Philippines. There are around 1,800 MPAs in the country, but most are very small. Too small for wide-ranging animals like large sharks. Just two MPAs make up 85% of the total no-take (off-limits to fishing) area in the country.
Tubbataha Reefs Natural Park, the larger of the two areas, covers 1,000 square kilometres in the Sulu Sea. Tubbataha is an iconic marine reserve. A map of the park is shown on the 1,000 Peso note, the largest banknote in circulation in the Philippines. The reefs have been protected since 1988, and the area was declared a UNESCO World Heritage Site in 1993.
While there’s been a lot of excellent science done at Tubbataha, there had been no dedicated shark surveys prior to 2015. The scientists at LAMAVE became intrigued after hearing from dive operators that their trips to the park were getting better every year. We were all keen to know if the numbers of these highly-mobile predators were recovering.
Ryan Murray from LAMAVE, the lead author on the study (published in the Journal of Asia-Pacific Biodiversity), spent months living at the ranger station at Tubbataha. This structure, on stilts to minimise impact, is the only permanent habitation in the park. It’s staffed year-round by marine park rangers, consisting of Tubbataha Management Office staff, the Philippine Coast Guard, Philippine Navy, and representatives from the local government unit of Cagayancillo. They conduct regular patrols and monitor vessel activity throughout the park with a radar system.
The rangers helped Ryan to deploy underwater video systems all around the park to 100m depth. A bait bag was attached to encourage sharks to investigate the unit. We also used the WWF Philippines vessel, the M/Y Navorca, to move divers around the park for underwater visual surveys along the reef margins, at around 5-25m depth.
At least 23 species of sharks and rays use the park, from whale sharks and tiger sharks to gorgeous eagle rays, but it’s the reef sharks – whitetips and grey reefs – that dominate, through sheer force of numbers. Their densities are some of the highest recorded worldwide, more than three times those seen in no-take areas of the Great Barrier Reef in Australia. It’s shark heaven. Lots of other big predators are present too, from dogtooth tuna to massive schools of jacks.
How has Tubbataha been so successful? Well, it does have some natural advantages. It’s a big area, which definitely helps. The reefs are around 170km from the nearest major port in Palawan, though it’s still within easy range of the fishing fleet.
Really, these fantastic results are a tribute to good management. The foresight to protect the area in the 1980s has allowed multiple generations of reef sharks – which reach adulthood at around 10 years – to live and reproduce without fishing pressure. These gains compound over time.
Similarly, the first couple of years after the park was created were tough. There was a lot of attempted illegal fishing activity, and the rangers had to be vigilant. After a while, when it was clear the park was being patrolled carefully, such attempts became rare. The presence of small, but mean-looking naval vessels in the park are a powerful deterrent to poaching.
The main lessons? Larger MPAs, with no fishing, can support more sharks. Active enforcement and time are the other main success factors. The best time to protect a habitat is before it is damaged by people. The next best time is today.
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