South African National Parks (SANParks) recently co-published a study on the global analysis of industrial fishing and shark movements. The study measures the degree of overlap and associated risk to sharks from fishing and proposes high seas Marine Protected Areas (MPAs) as a partial solution. More than 150 scientists collectively tagged and tracked sharks of different species with 12 South African scientists from 16 collaborating South African institutions providing satellite tagging data for white sharks, bull sharks and tiger sharks tagged along the South African coast.
SANParks Marine Biologist at the Cape Research Centre, Alison Kock said, “two thirds of the species tracked in this study are considered threatened or endangered by the International Union for the Conservation of Nature (IUCN) and there is limited management of these species on the high seas (high seas are seas outside any country’s jurisdiction). One quarter of the habitats of oceanic sharks fall within active fishing zones, which may threaten these iconic ocean predators.’’
She said this discovery, published in the scientific journal Nature, demonstrates an urgent need for conservation efforts to protect pelagic sharks, which are reported to be in decline. The study is also timely given the current international discussions and policy negotiations for high seas management under the United Nations Convention on the Law of the Sea.
Kock highlighted that 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 and the extent of habitat overlap with industrial fisheries has been difficult to determine,’’ continued Kock.
The combining satellite-tracked movements of pelagic sharks and global fishing fleets lead by David Sims and his colleagues provided a global estimate of space-use overlap. She said 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. “The results reveal that 24% of the space used by sharks in an average month falls under the footprint of longline fisheries, which are responsible for catching most sharks from the open ocean’’ added Kock.
In conclusion, Kock said 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%) and sharks have few places in which they can take refuge from fisheries. “The results of this study provide the first step to implementing better management actions for sharks on the high seas. These include increased observer effort on fishing vessels to understand actual mortality associated with fishing activities, the designation on large-scale marine protected areas to conserve vulnerable species and habitats, and the use of technology to improve monitoring and enforcement.”
South African National Parks (SANParks) Corporate Communications
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Reynold “Rey” Thakhuli
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