Will orcas sink whale-watching boats because of noise pollution?

 

Orca whales jumping. Photo by Robert Pittman, Wikimedia Commons.

            Even if they haven't read the novel, most everyone knows the ending of Moby-Dick: the white whale sinks Captain Ahab's whaling boat, the Pequod, and all perish save Ishmael, who survives to tell the tale. So it may not have been entirely surprising to hear recent news reports of orcas (killer whales) attacking and seriously damaging fishing boats--already twelve boats this year. As it happens orcas have been well studied by not only by biologists but also by ecomusicologists interested in the sounds they make. Orcas find their food by echolocation; that is, by sending out sound signals and listening for the echoes to located prey. Orcas, like other whales, also communicate with one another via sound.

            Ecomusicologist Mark Pedelty made a documentary film, Sentinels of Silence, about how the propeller noise from powerful whale watching boats in the Salish Sea (the waters off the northwest coast of the United States and the southeast coast of Canada) upsets the orcas that live there, making it impossible for them to locate their food or one another. Whale-watching is a major tourist business in the area, but orcas are an already endangered species. This intrusion into the ocean sound commons undoubtedly makes it more difficult for orcas to survive. Animal rights activists fought the whale-watching industry and, with the help of Pedelty's film, were able to convince the government to regulate the noise pollution from the whale boats.

            The dozen orca attacks this year all occurred off the coasts of Spain and Portugal. Some scientists hypothesize that these orcas may be attacking those fishing boats for vengeance: either because the boats are interfering with the orcas' food supply, because the orcas get entangled in the fishing gear, or even because one of them was struck by a fishing boat. None of the scientists mentioned the possibility that propeller noise was a reason for the orca attacks. The scientists attribute agency to the orcas and have observed a female named White Gladis "teaching" the other orcas to attack the boats. This behavior hasn't yet been observed in the Salish Sea, but it's not beyond possibility.