Tracking the great hammerheads... to save them

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Tracking the great hammerheads... to save them

February 24, 2017 - 23:18
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It has not been easy to protect and manage the great hammerhead shark population as there is still much we don't know about its behaviour. However, a new study uncovers a glimmer of hope for this species.

Scientist using the non-invasive laser photogrammetry technique on this great hammerhead shark.

Scientists say that by finding out about the sharks' movements and use of specific geographic areas, we can limit interaction between them and people.

“Knowing when the animals are likely to be in certain places will be critical in developing effective management strategies. For example, our data could be used to create so-called 'time-area closures', where certain areas are closed to particular activities, like fishing, at different times. The aim would be to reduce harmful interactions with the sharks,” said lead researcher Dr Tristan Guttridge from the Bimini Biological Research Station, Bahamas.

The study, published recently in Frontiers in Marine Science, looked at the temporal and spatial aspect of the sharks' movements. To track the shark's movements, the researchers tagged the great hammerhead sharks with acoustic and satellite tags, and used photo identification and laser photogrammetry.

This study is the first to provide evidence that Great Hammerheads return to particular areas after migrations to find food, pup or mate. This discovery makes them vulnerable to fisheries and has great implications for marine management, and the development of MPAs (Marine Protected Areas).

“Thanks to the combination of methods used by the authors, the study has revealed complex movement patterns, with broad-scale migrations across jurisdictions as far North as Virginia, USA, as well as seasonal site fidelity in Florida and the Bahamas,” said Dr Charlie Huveneers of the Southern Shark Ecology Group in Flinders University, Australia.

To be effective, management strategies would need to extend beyond jurisdictional and international borders. “We have only just scratched the surface of defining key spatial hotspots, but clearly for these highly mobile sharks, we need international cooperation,” said Dr Guttridge.

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