Although they are not usually targeted, sharks and certain groups of sponges and cold-water corals can be impacted by boats trawling for fish in deep-sea fisheries at depths of between 200 and 2 000 metres.
In most cases, the survival rate of these deep-sea bycatch species after being released back into the sea is low.
Few countries are currently providing detailed information on deep-sea bycatch, making it difficult to understand the effects these fisheries are having on vulnerable marine ecosystems.
“There is a large variety of weird and wonderful species down there that play an important role in deep-sea ecosystems,” said Johanne Fischer of FAO’s FishFinder Programme. “But scientists and fishers alike can have trouble identifying them as there are few identification tools available. Instead they tend to lump species together as ‘deep-sea sharks’ when they report their catches.”
In general, catch reporting on cartilaginous fish – sharks, rays, skates and chimaeras, all of which have skeletons made of cartilage rather than bone – is poor compared to those on bony fish.
Globally, and including all types of fisheries, only 36 percent of cartilaginous fish catches were identified at species or genus level in 2011, compared to more than 75 percent for bony fish.
“We need a clearer picture of what’s happening, and this is especially true for the deep seas,” said FAO Fishery Analyst Jessica Sanders. “The new FAO deep-sea guides will help fishers provide more detailed information, and as a result countries will be in a better position to implement FAO’s International Guidelines for the Management of Deep-sea Fisheries in the High Seas, which set out recommendations for the conservation and management of vulnerable ecosystems.”
FAO is supporting the implementation of sustainable fisheries management practices outlined in the International Guidelines through a full-scale programme on Deep-sea Fisheries, which includes improving data reporting by developing identification guides and training programmes.
Largest habitat on earth
Deep seas are the largest habitat on earth, covering 53 percent of the sea’s surface, and fishers have increasingly been exploiting their resources in recent decades.
Far from the coasts, the sustainable management of the world’s deep-sea fisheries is complex.
Deep-sea fisheries in Areas Beyond Natural Jurisdiction (ABNJs) are outside the control of any one country and frequently take place on the ocean’s submerged underwater features such as seamounts. These ecosystems are often sensitive as many deep-sea species are slow to mature and reproduce, making them especially vulnerable to overfishing.
“More than in any other marine area, ensuring the long-term conservation and sustainable use of deep-sea marine living resources relies on the willingness of countries, and fishers themselves, to adopt sustainable and responsible management strategies,” said FAO’s Jeremy Turner, coordinator of Common Oceans, the ABNJ programme jointly managed by FAO and the Global Environment Facility.
Series kicks off with Indian Ocean
The first guide in the FAO series on deep-sea vulnerable species focuses on the Indian Ocean, one of the most diverse and poorly known regions with regard to deep-sea cartilaginous fish.
In total, the Indian Ocean is home to about 36 percent of the world’s deep-sea cartilaginous species: 117 deep-sea sharks, 61 skates and rays, and 17 chimaeras – shark-like fish also known as ghost sharks.
Species include the half-metre-long cookiecutter shark, known for gouging cookie-cutter shaped mouthfuls out of larger animals, as well as the bignose shark, the false catshark and the deep-water stingray, all of which can grow to around three metres.
The guide is laminated for use at sea and includes colour illustrations for the sharks most difficult to identify or most commonly caught, as well as entries for other species that are often misidentified.
Developed by FAO’s Deep-sea Fisheries Programme in close collaboration with FAO FishFinder and with financial support from Norway and Japan, the guide is accompanied by a more in-depth species catalogue that includes detailed scientific information.
The series will eventually include sponges and corals and cover all of the world’s most important deep-sea fishing areas.
FAO and sharks
FAO has long been working to improve the management and conservation of sharks. An International Plan of Action for the Conservation and Management of Sharks adopted in 1999 stipulates that shark-fishing countries should produce national programmes for the conservation and management of sharks.
So far 18 of the world’s 26 top shark-fishing nations have a national plan on sharks and five more are in the process of developing one.