Dolphin whistles may help predict mass strandings and help prevent them

Véronique LaCapra, Woods Hole Oceanographic Institution
John Milliken, Wellfleet assistant harbormaster; Sam Walkes, a summer student fellow at WHOI; and Alex Bocconcelli, a research specialist at WHOI, prepare an underwater recording device to detect and record the calls of dolphins in the harbor.

A team of researchers studying dolphins at Wellfleet Harbor on Cape Cod said they might have found a way to prevent mass stranding events by listening to dolphin whistles.

Laela Sayigh — a lead investigator on the team, a research specialist at the Woods Hole Oceanographic Institution, and an animal behavior professor at Hampshire College — said a mass stranding is when two or more healthy animals come ashore, excluding mother-calf pairs.

“People can’t stand to see dolphins mass strand,” she said in a telephone interview last week. “It’s really heart-breaking to see these healthy animals coming up on the beaches and dying.”


Wellfleet Harbor, with its extreme tides and “trap-like” geography, is a hotspot for mass strandings, Sayigh said.

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The International Fund for Animal Welfare tries to return the animals to the water, but the process is time-consuming and expensive, and there’s no guarantee rescuers will arrive in time to save the dolphins, she said.

“Sometimes their body condition can be quite compromised at that point,” she said.

She and her team received a grant to test the feasibility of a system that relies on a recording device that picks up sounds underwater, including the signature whistles dolphins use to identify themselves, so scientists can detect mass strandings before they happen, Sayigh said.

Since the team started their work in 2014, they’ve been able to pick up the whistles and interpret them in relation to mass strandings, Sayigh said.


Previous research on bottlenose dolphins suggests that the rate of signature whistles is correlated with stress, and when Sayigh and her team looked for them in their recordings, they found they occurred more frequently in the recordings taken just before mass strandings.

“In this stressful, pre-stranding context, we have a situation where animals are making a lot of signature whistles,” she said.

That information was promising enough from a study meant only to determine if there was a way to detect the deadly events, but when funding runs out in January, the team is hoping to receive another grant in order to further their research.

The next step is seeing if that information can be used and interpreted quickly enough to be effective, Sayigh said.

The team plans to create an automated recording device that not only detects the whistles, but sends them to analysts on call at the IFAW or other rescue organizations, she said. One of the researchers on the team, Mark Baumgartner, a marine ecologist at the Woods Hole Oceanographic Institution, has already developed a similar device for whales.


Once the pitch tracks are sent, someone on the rescue team would immediately analyze them for signature whistles and determine if there might be a mass stranding so the animals can be herded away from shore, Sayigh said, but they have to be able to do so quickly.

“Timeliness is incredibly important in that scenario,” she said.

Furthermore, Sayigh said the research might also help scientists understand why animals mass strand.

No one knows why the animals come ashore if they’re healthy, but Sayigh suggested the phenomenon is likely linked to the strong social structure of pods. Dolphins swim in groups, which means they could be following one another into trouble.

“Why they happen really has been an enduring mystery,” she said. “This study has the potential to give us a little glimpse . . . into what’s going on behaviorally when they are about to strand.”

Alyssa Meyers can be reached at Follow her on Twitter @ameyers_.