Shark bite study: We seem like seals

Many great white shark bites of humans may be a case of mistaken identity because surfers and swimmers can look like the apex predators’ favorite food, according to new research.

To a juvenile white shark, people who swim and paddle surfboards bear a strong resemblance to seals and sea lions, the researchers from Australia’s Macquarie University found.

“Surfers are the highestrisk group for fatal shark bites, especially by juvenile white sharks,” said lead author Laura Ryan, a researcher in animal sensory systems at Macquarie University’s Neurobiology Lab.

“We found that surfers, swimmers and pinnipeds (seals and sea-lions) on the surface of the ocean will look the same to a white shark looking up from below, because these sharks can’t see fine details or colors,” she added.

The last recorded shark bite off of Massachusetts was in 2018, when a man was killed while boogie boarding on the Cape. It was the first shark fatality in the Bay State since 1936.

This study out of Australia will help the scientists better understand why certain sharks bite humans, Ryan said. Also, scientists at the university’s Neurobiology Lab are now working on vision-based devices to potentially protect surfers and swimmers from shark bites.

This latest study, published in the “Journal of The Royal Society Interface,” was a practical test to understand how sharks see. The researchers explored the neuroscience of white sharks’ visual systems.

The team compared underwater video of rectangular floats, seals and sea lions swimming, humans swimming different strokes, and humans paddling on surfboards in an aquarium.

“We attached a Gopro to an underwater scooter, and set it to travel at a typical cruising speed for predatory sharks,” Ryan said.

The researchers were then able to simulate the way that a juvenile white shark would process the movements and shapes of different objects.

The results were illuminating, Ryan said: To a juvenile white shark, when humans swim and paddle surfboards, they bear a strong resemblance to seals and sea lions.

Great white sharks typically target smaller, young pinniped pups. In the study, smaller surfboards were harder to distinguish from the pinnipeds, so they might be more tempting than longboards or stand-up paddleboards to white sharks.

Most sharks are likely colorblind. As a result, colors on boards and wetsuits are unlikely to change sharks’ impressions of floating humans.