Sharks at risk in fisheries
About one-quarter of oceanic shark habitat is actively fished, leaving sharks with limited places to hide from longlines and nets.
A new study by Australian and international researchers has found that around one quarter of the habitats of oceanic sharks fall within active fishing zones, which may threaten the iconic ocean predators.
The discovery demonstrates an urgent need for conservation efforts to protect sharks.
Pelagic (or oceanic) sharks are highly migratory, covering vast areas of the ocean — including areas targeted by fisheries.
Large pelagic sharks account for around half of all identified shark catches from fisheries. The extent of habitat overlap with industrial fisheries has been difficult to determine, as data from fisheries about catch numbers can be incomplete.
Combining satellite-tracked movements of pelagic sharks and global fishing fleets, researchers were able to make a global estimate of space-use overlap.
A total of 1,681 large pelagic sharks (23 species) tagged with satellite transmitters were followed, and fishing vessel movements were monitored by a safety and anti-collision system.
Their results reveal that 24 per cent of the space used by sharks in an average month falls under the footprint of pelagic longline fisheries, which are responsible for catching most sharks from the open ocean.
Areas of ocean that are frequented by protected species, such as great white sharks and porbeagle sharks, had higher overlap with longline fleets (around 64 per cent).
These findings indicate that pelagic sharks have limited places in which they can take refuge from fisheries.
The authors suggest that conservation efforts are needed to protect these sharks, and that designated large-scale marine protected areas around regions of shark activity could be one solution.