Shark hotspots ‘tracked’ by fishing vessels

Blue shark Prionace glauca. Credit: Neil Hammerschlag, SharkTagging.com

A new study suggests that current ‘hotspots’ of shark activity are at risk of overfishing, and that the introduction of catch quotas might be necessary to protect oceanic sharks.

Tens of millions of ocean-dwelling sharks are caught by fishing each year, and catch rates have declined significantly for many species, yet oceanic shark fishing remains largely unregulated. A lack of data on where sharks are likely to encounter fishing vessels hampers current conservation efforts.

The research, published in Proceedings of the National Academy of Sciences of the U.S.A., found significant geographic overlap between hotspots of oceanic shark distribution and fishing activity.

“Many studies have tracked sharks, and many studies have tracked fishing vessels, but fine-scale tracking of sharks and fishing vessels together is lacking, even though this should better inform how shark fisheries should be regulated,” says Professor David Sims of the University of Southampton, UK, the senior author of the study.

An international team of researchers from the UK, Portugal, Spain and U.S.A. tracked more than 100 sharks from six different species by satellite across the entire North Atlantic, one of the most heavily exploited oceans. Concurrent with the shark tracking, the scientists tracked 186 Spanish and Portuguese longline fishing vessels using GPS to quantify the overlap in space and time.