Between Dives, Orcas Take Only a Single Breath

A new study finds the black-and-white marine mammals tend to make shorter, shallower dives compared to humpback and blue whales, making orcas the “sprinters” of the ocean

Orcas swimming in the ocean as seen from above
The researchers used drone footage and tracking devices to analyze the behavior of 11 orcas in the northern Pacific Ocean. UBC and Hakai, drone pilot Keith Holmes

Scientists know a lot about orcas—they live in matrilineal groups, are highly intelligent and can live up to 90 years, for instance. But even some of the most basic questions about orca behavior remain unanswered.

Now, new research offers insights into the diving and breathing habits of orcas. These black-and-white marine mammals, often referred to as “killer whales,” tend to make short, shallow dives that last less than a minute. They also only take one breath between each dive, researchers report this month in the journal PLOS ONE.

“Killer whales are like sprinters who don’t have the marathon endurance of blue and humpback whales to make deep and prolonged dives,” says study co-author Andrew Trites, a zoologist at the University of British Columbia in Canada, in a statement.

Understanding how orcas breathe can give scientists insight into their energy needs. For their study, the researchers wanted to understand how much food orcas must eat to survive, as well as how much energy they expend while resting, traveling and hunting—knowledge that will come in handy for conserving imperiled groups of the animals.

The orcas that live off the western coast of North America are in trouble. Southern resident killer whales, which spend much of the summer and fall in Washington’s Puget Sound, have been listed under the Endangered Species Act since 2005; around 70 individuals of this group remain in the wild. Northern resident killer whales, meanwhile, are considered “threatened” in Canada, with about 300 individuals remaining in their north Pacific range.

Scientists used drones and tracking devices to observe 11 northern and southern resident orcas near British Columbia, Canada. The tracking devices, which were attached with suction cups for about 20 hours before falling off, were “essentially like putting a Fitbit on the animals,” says study co-author Beth Volpov, a marine biologist at the University of British Columbia, to Popular Science’s Laura Baisas. “If a whale is tagged, we’re looking at that whale from above to the nearest second.”

Combining data from the trackers and drones, the team analyzed 8,118 dives in total. The orcas in the study took 1.2 to 1.3 breaths per minute while resting and 1.5 to 1.8 breaths per minute while traveling or hunting. Most dives lasted less than a minute, though one adult male did spend more than eight minutes beneath the surface.

Their analysis also confirmed the long-held belief that orcas take just one breath between dives.

For comparison, humans take roughly 15 breaths per minute when at rest and 40 to 60 breaths per minute while exercising. The orcas’ breathing rates are the “equivalent of holding your breath and running to the grocery store, shopping and coming back before breathing again,” Volpov says in the statement.

After confirming that orcas take just one breath before plunging underwater, the researchers were able to calculate how much oxygen orcas consume per minute. In the future, those numbers will help scientists understand how much energy orcas need and, in turn, how many calories they must eat per day. Once they know that, they can figure out whether northern and southern resident orcas have access to enough food in their habitat, which will inform conservation efforts.

The new research is “consistent with [other findings], which means we’re on the right track to coming up with a good solution for the southern resident killer whale population,” says Janine McNeilly, a former orca researcher at Simon Fraser University who was not involved with the study, to CBC News’ Isaac Phan Nay.

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