Sexually frustrated dolphin blamed for 18 attacks on swimmers in Mihama, Japan

A sexually frustrated dolphin is causing problems in Japan. Photo / 123RF

A lonely dolphin acting out of sexual frustration is believed to be the culprit behind a spate of attacks on swimmers in Japan this summer.

Since July this year, 18 people have been hurt in dolphin attacks near the seaside town of Mihama, with some requiring dozens of stitches.

Posters warning beachgoers of the menace feature an open-mouthed dolphin baring razor-like teeth. It says the mammals “are known to be dangerous to humans” and warns people to get out of the water if they are seen nearby.

Stressed by crowds of bathers

Wild dolphins rarely attack humans but have been known to bite or pull people underwater if they feel threatened or harassed.

This was reportedly the case when one man was killed in 1994 in Sao Sebastiao, Brazil after an initially friendly dolphin called Tiao reportedly became stressed by the attention of crowds of bathers who wanted to play with or even torment him.

Like Tiao, Japan’s problematic mammal is believed to be a solitary male bottlenose dolphin, who may also be responsible for injuring swimmers in 2022 and 2023, and trying to press his genitals against them.

Putu Mustika, a lecturer and marine researcher at James Cook University in Australia, told the New York Times dolphins can inadvertently harm humans by dint of their sheer strength when acting out mating behaviours.

“Dolphins, when they are mating, can be very wild,” she said, adding that the act of lunging on top of a human could be seen as a sexual act and a sign that the dolphin was “horny, lonely”.

This dolphin could also be naturally aggressive or aggravated by humans trying to touch it, she said.

Broken ribs and bites

At least six people were also injured in the same area last year, with one man in his 60s suffering broken ribs and bites to his hand after he was rammed by a dolphin.

Giovanni Bearzi, a zoologist and president of the Dolphin Biology Conservation in Italy, told Live Science at the time humans tend to see dolphins as “invariably ‘nice’ animals”, overlooking the fact they are extremely powerful.

“Our unaware or overly ‘friendly’ behaviour may trigger aggression,” he said.

Japanese authorities have tried a number of measures to try to stop the attacks, including installing dozens of underwater acoustic devices designed to deter dolphins and/or limiting swimming hours on some beaches.