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From 1888 to 1912, a Risso’s dolphin named Pelorus Jack became a tourist attraction in New Zealand for escorting ships from Pelorus Sound to French Pass. The dolphin would ride the pressure waves created by the ships—an activity known as bow riding, which dolphins and other cetaceans have likely been engaging in since ships first set out to sea. The Greeks, one of the great early seafaring peoples, recorded dolphins bow riding in the eastern Mediterranean and Aegean Seas.
Yet in modern times, cetaceans are bow riding alongside motorized vessels. It’s a risky maneuver given that ships and ship noise are harmful to the animals. So why do they do it?
One veteran marine biologist surmises that bow riding is primarily undertaken by juveniles and young adults—similar to how human teenagers engage in risky pleasure seeking.
“When [I was] young … I stood right next to the speakers and danced my head off,” says Kathy Heise, a marine biologist who has studied cetaceans on the British Columbian and Alaskan coasts for more than three decades. “I’ve seen older-looking females come in and chase their offspring off the bow. There is some recognition it’s not a good place to be.”
In a 1960 paper, researchers suggested dolphins and porpoises may deliberately use a ship’s waves to propel themselves through the water, surmising that “large cetaceans could very well use wave-riding techniques for migratory travel.” While that theory is no longer given serious consideration, plenty of reasons are offered for bow riding.
“It’s an interesting phenomenon, for sure,” says Erin Ashe of the Seattle-based Oceans Initiative. She studied Pacific white-sided dolphins for her doctoral degree and agrees that younger individuals are more likely to bow ride.
Ashe has seen juveniles jumping and splashing in front of her research vessel, seemingly to encourage it to go faster and produce bigger waves. Dolphins are even known to antagonize large whales in hopes of forcing them to lunge forward and create waves.
Killer whales, too, are known to approach vessels on rare occasions to ride their waves. Ashe recalls seeing killer whales riding alongside cruise ships and freighters in British Columbia.
Heise remembers a young, social killer whale named Bubbles that followed in the wash of boat propellers in Alaska. “We’ve also watched killer whales surfing in waves generated by swells and they totally look like they’re having a good time,” she says.
Ashe readily accepts that bow riding could simply be a form of play, but suggests it may also have a greater purpose. It’s possible, she suggests, that cetaceans may approach ships to get a closer look—an adapted form of a natural behavior. “Animals that inspect their predators have a higher rate of survival than those that don’t,” she says.
Another theory is that ship noise can cause prey such as herring to school up and become easier to catch, though Ashe notes that a dolphin distracted by bow riding may also be more vulnerable to predation.
Ultimately, bow riding might be an evolutionary trait or a cultural activity handed down from one generation to another. “It may be ingrained in who they are,” Ashe concludes. “Although it may not be good for them, including effects on their hearing, they are still compelled to do it.”
Heise agrees: “People don’t always do what’s adaptive, and I don’t think animals are any different.”