Rogue Dolphin Attacker May Be Lonely

Ah, dolphins: So cute, social, and intelligent—except when they're angry, lonely, and perhaps a little sexually frustrated, in which case they can be dangerous, aggressive, and more than a little unfriendly toward humans. Such is the case of a stretch of Japanese shoreline, reports the BBC, which has been plagued by a series of attacks on swimmers believed to be the work of a lone bottlenose dolphin. Beginning in 2022, at least 25 different attacks have taken place near the town of Mihama, including 18 this year alone. None were fatal, but one swimmer suffered several broken ribs and bites that required stitches. Based on sightings of one dolphin's dorsal fin—the equivalent of a dolphin's fingerprint—experts believe they have a single culprit, reports the New York Times.

"It is reasonable to assume that it is the same individual, as the wounds on the tail fin are similar to those of the dolphins seen off the coast last year, and it is rare for dolphins, which normally move in groups, to be alone for such a long time," cetology professor Tadamichi Morisaka tells NHK. Some beaches have installed ultrasonic wave emitters as a deterrent and signs warning swimmers to get out of the water at the sight of a dolphin, reports Japan Today, while the Times notes that others have lifeguards constantly scanning the waves for a sign of a dorsal fin. It's a good reminder that dolphins can be dangerous, with the ability to not only bite, but "drag you into the sea, which could be life-threatening," warn officials.

Theories abound: It's possible the dolphin was "ostracized from its own community and (may) be seeking alternative companionship," says biologist Simon Allen of the Shark Bay Dolphin Research project. Or "hormonal fluctuations, sexual frustration, or the desire to dominate might drive the dolphin to injuring the people it interacts with." The dolphin may also have had a bad experience with humans, who can be prone to doing dumb things like attempting to ride the wild animal or poking their fingers in its blowhole. And dolphins, like elephants, "have a good memory ... (and) will remember who mistreated them before," says marine mammal expert Matthias Hoffmann-Kuhnt at the National University of Singapore. (More bottlenose dolphin stories.)