The bubble-feeding trick spreads through humpback whale social groups

Humpback whales work together to catch fish by surrounding them with bubbles

Jenn Dickie/North Coast Citizen Society

An innovative way of feeding spread rapidly through humpback whales in the fjords of western Canada, a clear example of how cultural knowledge can help animal populations survive.

Bubble net feeding is a group hunting technique in which whales blow bubbles at caged fish, then dive up together and swallow them down.

“It’s an activity that’s done collaboratively with respect to the level of coordination and division of labor,” he says Ellen Garland at the University of St Andrews in Great Britain.

This behavior has been documented for decades among humpback whales (Megaptera novaeangliae) in Alaskan waters, and scientists have recently begun to observe it in the northeastern Pacific population off Canada.

But it’s difficult for researchers to determine whether complex behaviors like this are transmitted through social learning—rather than being independently discovered by multiple individuals.

To detach a process, Éadin O’Mahony at the University of St Andrews and her colleagues analyzed field observation data from 2004 to 2023, focusing on 526 individuals living in the Kitimat fjord system in British Columbia on the territory of the Gitga’at First Nation.

The team identified the whales using images of their tail flukes, which are unique to each animal. The data show that 254 individuals performed bubble net feeding at least once, and about 90 percent of these events occurred cooperatively.

This behavior also seemed to begin to coincide with a major offshore heat wave in the Northeast Pacific after 2014 that reduced price availability.

“With a heat wave, as the availability of prey decreased, the whale’s ability to change its feeding behavior would help it maintain its daily caloric intake,” says O’Mahony.

Whales were more likely to accept bubble net feeding if they regularly socialized with others who already used the technique. Bubble-net feeding was probably introduced to the region by whales migrating from elsewhere in the northeast Pacific, but the pattern mainly points to behavior spreading through local social networks carried by stable groups and influential individuals.

“What we’re seeing from the warm years forward is an increase in whales that were no longer participating in bubble net feeding in the area,” says O’Mahony.

Humpback whales’ ability to pass on knowledge through social groups may be vital to their survival, and understanding their culture could help us protect them, scientists say.

“It’s not just about how many animals are left, but whether the social behaviors that make the population work are coming back as well,” he says. Ted Cheesemanco-founder of the citizen science platform Happywhale, who was not involved in the study.