‘Sexually frustrated’ dolphin believed to be behind attacks on swimmers, experts say

Experts have weighed in on a string of bloodied attacks on swimmers at a popular beach on the coast of Japan.

It’s not just the sharks you should be scared of while swimming in the clear waters off the coast of Mihama, Japan — it’s the dolphins, too.

To date, around 18 attacks have occurred on popular beaches like Suishohama beach, with swimmers receiving wounds so deep, they’ve needed stitches. Six of those occurred last year alone, with one including a primary-school aged boy who needed stitches to his finger.

Now, experts say they believe what’s causing the attacks, and it’s not from the tooth of a shark.

A bottlenose dolphin is believed to be responsible for attacks on humans. Photo: iStock

Speaking to the BBC, Biologist Dr Simon Allen believes the culprit is a single male bottlenose dolphin — who has likely been kicked out of its pod “and be seeking alternative companionship”.

“Bottlenose dolphins are highly social animals and this sociality can be expressed in very physical ways,” Dr Allen, who is also a principal investigator with the Shark Bay Dolphin Research project, told the publication.

“Just as in humans and other social animals, hormonal fluctuations, sexual frustration or the desire to dominate might drive the dolphin to injuring the people it interacts with. Since they are such powerful animals, this can lead to serious injury in humans.”

A fellow marine biologist from the National University of Singapore said the attacks on humans may be driven by a multitude of caused — and not just hormonal or sexual frustrations.

Dr Matthias Hoffmann-Kuhnt said the attacks, focusing on ribs breakages and bites to limbs and fingers, were likely the result of humans getting too close to the dolphin and the mammal simply defending itself.

Bottlenose dolphins. Picture: Peter Fuller

“Most of the time, in my experience, this is more a defensive behaviour when humans get too close to these dolphins and do not know how to conduct themselves,” he said

“It is no wonder that the animals then turn aggressive or at least protective against humans in the water.”

Dr Hoffmann-Kuhnt added that the particular dolphin that appears to be at the centre of these attacks may have been harmed by a human previously, given they have sharp memories similar to elephants.

Last year saw a string of incidents involving a dolphin in the town of Mihama, Fukui prefecture in Japan.

Four swimmers were injured by a dolphin, including one man in his 60s, who suffered broken ribs and bites to his hands. Another man, in his 40s, sustained arm bites in a separate incident at the same popular beach on the same morning. Two more people were injured, presumably by the same dolphin, later in the day.