Two whales nearly 100km apart dive at the same time

Two bowhead whales in the Arctic synchronize their dives, demonstrating the ability to communicate by sound over extremely long distances.

Every January to May, baleen whales flock to Qeqertarsuaq Tunua , a large bay on Greenland's west coast, to feast on plankton. In 2010, two bowhead whales ( Balaena mysticetus ) of a baleen whale group entered the bay to feed. About 60 miles apart, something extraordinary happened: They began to synchronize their dives.

Bowhead whales can synchronize dives when they are within communication range of each other. (Photo: Vicki Beaver/Alaska Fisheries Science Center/NOAA Fisheries)

In a new study published in the journal Physical Review Research , the authors suggest that the pair of whales, although unable to see each other, can still hear each other's sounds. The observation provides potential evidence for a 53-year-old hypothesis, Smithsonian reported on October 5.

Baleen whales are generally thought to be solitary. However, some scientists believe they travel in dispersed pods, communicating over distances of hundreds of miles. Biologist Roger Payne and oceanographer Douglas Webb first proposed the idea of ​​the acoustic herding hypothesis in 1971.

Bowhead whale diving behavior can seem chaotic and unpredictable at first glance, with dives lasting hours and then stopping for no apparent reason, according to Evgeny Podolskiy, an environmental scientist at Hokkaido University in Japan and lead author of the new study.

Podolskiy and his colleagues wanted to find order in this seemingly randomness. Using satellite tags, the team collected data on the depth and dive locations of 12 bowhead whales in the Arctic for 144 days. Then they applied complex algorithms based on chaos theory. As they worked through the calculations, patterns began to emerge.

First, the team found that the whales' dives tended to follow a 24-hour cycle , with shallower dives in the morning and deeper dives in the afternoon. This is consistent with the phenomenon of Daily Vertical Migration (DVM) —the journey of plankton and other small organisms from the ocean surface to the deep sea and back. They also found that the whales made their deepest dives in the spring, when DVM is most active in the Arctic.

What surprised Podolskiy, however, was a second pattern: synchronized dives by pairs of bowhead whales in Qeqertarsuaq Tunua Bay. The researchers weren't sure how the animals were related, but they synchronized their dives over seven days, when they were within 60 miles of each other. That, the team calculated, was the maximum audible range for whales in the area. " This is incredibly strange underwater behavior. It's very interesting ," Podolskiy said.

Podolskiy also added that it's possible that the synchronization is just a coincidence. It's possible that ocean conditions are causing the whales to dive in different locations at the same time. However, synchronized dives happen over multiple days, making it statistically unlikely. "We currently believe that it has something to do with communication ," he said.