5 October 2016
Great white sharks migrate over huge distances, making it tricky to track specific individuals through the seasons. Now, a project hopes to automate their identification from photographs of their fins.
The technique, known as “finprinting”, uses the unique contours of a shark’s dorsal fin as a biometric – rather like a human fingerprint or iris. Researchers have scrutinised fins to identify sharks for years, sometimes using software to help, but the new project is an attempt to make the whole process automatic.
The system, developed by Ben Hughes and Tilo Burghardt at the University of Bristol in the UK, has been trained on 240 photographs of shark fins. It picks out recognisable portions of the fin contour, not just entire fins. This means that images of fins that later become partially damaged might still be useful for identification.
In tests, the software was able to analyse a picture of a shark fin and say, with an accuracy of 81 per cent, whether it belonged to a known individual or not.
The approach should help researchers keep tabs on revealing behaviour in shark migrations. In 2005, for instance, Michael Scholl, then at the White Shark Trust, and his colleagues reported an astonishing finding: a satellite tag on a great white nicknamed Nicole showed that she had travelled from South Africa to Australia and back within nine months.
This was a groundbreaking insight into the wanderlust of the mysterious species – but after that, observations of the shark ran cold. “In November, she left, but we didn’t have time to put a satellite tag on her, which was a big shame,” says Scholl. “She was never spotted again.”
Scholl still receives emails from shark enthusiasts asking what happened to Nicole. So far, he has had to reply that he does not know. The new system might one day spot her.