Wetenschap - 11 februari 2016

Tagging to save the white shark

tekst:
Hilde de Laat

A new tagging technique could help identify and provide protection in areas with a lot of white sharks. And this is much needed as there are only 3500 specimens left, fewer than the number of wild tigers. This was explained by Oliver Jewell, a researcher at the Netherlands Institute for Marine Research NIOZ, on a science day at the Wageningen graduate school WIAS on 4 February.

Witte haai met satellietzender. Foto: Phillip Colla

White shark with sattelite tag. Photo: Phillip Colla

It is not easy to keep track of sharks. Unlike seals or whales, they rarely come to the surface so that data from tags cannot be transmitted.

Acoustic tags and receivers provide a solution to this. A tagged shark which swims past a receiver is then registered. But such receivers have limited reception, so the method cannot be applied out at sea. Nevertheless, results have been booked with the acoustic tags. Sharks are often spotted, for example, in places with a lot of seals. Comparing the data on the two species reveals that seals often hide in the seaweed on reefs. It is precisely at places where the seals cross expanses of water without reef or seaweed that the shark attacks.

Jewell is now testing new tags which measure the movement, depth and temperature of the shark and can even produce video images. This makes it possible to track shark hotspots more accurately.


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