Dolphins' social habits spread virus

Three young male dolphins simultaneously break the water’s surface to breathe — first exhaling, then inhaling — before slipping back under the waves of the Chesapeake Bay.

“A perfect sync,” said Janet Mann, a dolphin researcher watching from a small skiff.

Synchronized breathing is something dolphins often do with close pals, like these males, or that mothers and calves do together, said Mann. It’s a way of affirming the relationships that are so important to these highly intelligent and social mammals, like a handshake or a hug among humans.

“It says, ‘We’re together,’” said Mann, who is based at Georgetown University.

While such close contact is essential to dolphin social bonds, sharing space and air can also quickly spread disease.

Mann and other scientists are trying to understand how a highly contagious and lethal disease called cetacean morbillivirus — related to measles in humans and first detected in Virginia and Maryland waters — can spread rapidly among dolphins along the Atlantic Coast, as it did from 2013 to 2015.

During that outbreak, more than 1,600 dolphins washed ashore on beaches from New York to Florida, according to the National Oceanic and Atmospheric Administration. Altogether, an estimated 20,000 dolphins died from the virus, and the region’s population of coastal dolphins shrank by about 50%.

“It’s much like COVID — it’s respiratory” in how it spreads, said Mann. “When dolphins breathe together at the surface, they’re sharing respiratory droplets just like we do when we’re talking or coughing on each other.”