Humpback whales herd fish using spiralling columns of bubbles

James Marshall
October 17, 2019

Once a bubble net surrounded the prey, the whale would swim through the net's center and gulp down anything caught inside.

Just as humans use fishing nets to capture scaley snacks, humpback whales rely on bubbles from their blowholes to round up dinner.

The research was conducted in waters off of Southeast Alaska by: Lars Bejder, director of the UH Mānoa Marine Mammal Research Program, UH Mānoa PhD student Martin van Aswegen and key collaborator Andy Szabo, Alaska Whale Foundation director, working with PhD student Will Gough and other members of Stanford University's Goldbogen Lab and the Bio-telemetry and Behavioral Ecology Lab at the University of California, Santa Cruz.

"Overlaying these two data sets is quite exciting".

Humpbacks sometimes blow bubbles underwater, creating a circular "bubble-net" that makes it harder for fish to escape. The whales don't eat during this period and use the Alaskan skrills to stock up on huge reserves to keep going. The researchers took identification photographs of the whales, then documented them with the help of a camera, a GoPro affixed to a long pole-so they could view the animals from above while standing on a walkway near the hatchery pens-and finally with a drone.

The MMRP's bubble-net research is helping scientists to understand how humpback whales feed, how often they need to feed, what they feed on and how fast their bodies change or grow.

Some 3,000 humpback whales visit Alaska every summer, and up to 10,000 are counted in Hawai'i for winter mating.

We've also seen Bryde's whales (Balaenoptera edeni) feeding this way, and bottlenose dolphins (genus Tursiops) off the coast of Florida use a similar cooperative hunting technique called mud-ring feeding, where they stir up a ring of sediment from the floor of shallow waters to trap schooling fish.

Humpback whale numbers increased after a ban on commercial whaling in 1985, and are no longer considered endangered, but in the last five years, there has been a substantial decline in humpback whale sightings.

"We're observing how these animals are manipulating their prey and preparing their prey for capture", Bejder explained.

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