Sharks of the deep in the Sulu Sea

  • Sharks
Years funded
  • 2023
  • Active
Project types
  • Conservation
  • Research

The dedicated deep-sea shark fishery of Cagayancillo, a small island in the Philippines’ Sulu Sea, is the focus of Titus’s work. Concerned by the vulnerability of poorly understood, haphazardly managed and rarely protected deep-sea ecosystems, Titus is looking to the future, when increasing pressure in the deep could cause the collapse of shark populations. He will explore what is driving deep-sea shark fisheries, search for critical deep-sea shark habitats and glean insights from local fishers to understand what alternative and supplemental livelihoods could improve the sustainability of deep-sea shark fisheries in the future.

Sharks of the deep in the Sulu Sea

Titus Cañete

Project leader
About the project leader

Having grown up far from the ocean and had little experience of swimming, I was always told to avoid deep water and developed a fear of what might lurk in the depths. It was only when my uncle introduced me to the world of diving that my fear transformed into curiosity and eventually into passion. After graduating from university with a degree in biology, I pursued a career in marine conservation and have been able to work and volunteer with many government and non-government organisations and agencies, all focusing on the conservation of the ocean’s inhabitants. My first...

Project details

Assessment of the Sustainability of Deep-Sea Shark Fisheries in the Sulu Sea, Philippines

Key objective

Our key objective is to assess the sustainability of the local deep-sea shark fishing industry in Cagayancillo, Palawan, Philippines, including its trade routes, to determine whether current techniques should be modified to ensure the protection of these vulnerable species and the sustainability of the local communities’ livelihoods.

Why is this important

Deep-sea organisms and ecosystems are extremely vulnerable to exploitation and since these ecosystems are poorly understood – and the deep-sea fisheries in the country are poorly documented – they and the services they provide could be lost. The project will give us a better understanding of the deep-sea shark fisheries of the Philippines, which will supplement management strategies and initiatives working towards the sustainability of the fisheries and to prevent overexploitation of deep-sea shark resources.


Even though most of the territorial waters of the Philippines are classified as deep-sea (more than 200 metres, or 656 feet, deep), little is known about these ecosystems, which means that the management of them is limited. Shark fisheries of the past almost brought many of the deep-sea shark populations to extinction following the boom and bust of the shark liver oil industry in the 1980s and 1990s. Such fisheries still exist today, but little is known about them because they are quite few and scattered. One of the few known dedicated deep-sea shark fisheries in the country can be found at Cagayancillo, a small island in the middle of the Sulu Sea where dogfish sharks are targeted for their liver oil (squalene). Under pressure from diminishing resources and increasing regulations in shallower waters, more and more fishermen may turn to fishing in deeper waters, but we don’t know whether such fishing can be done sustainably. As poorly managed fisheries lead inevitably to the collapse of the livelihood, research needs to be conducted to determine whether or not this type of fishery would be sustainable, to identify monitoring and management strategies and, when necessary, to introduce mitigating interventions.

Aims & objectives
  • To determine the economic and ecological sustainability and spatial patterns of the deep-sea fisheries around the island of Cagayancillo, Palawan.
  • To assess the current status of the deep-sea shark species in the area and the threats to them.
  • To identify potential critical habitats and Important Shark and Ray Areas (habitats important for one or more shark species that can be delineated and managed for their conservation).
  • To understand the perception of the locals involved in deep-sea shark fisheries with regard to supplemental and alternative forms of livelihood in order to support the sustainability of deep-sea shark fishing.