This is evident from a study published today in Royal Society Open Science, Researchers from the UH Hawai’i Institute of Marine Biology (HIMB) Marine Mammal Research Program (MMRP) and the Alaska Whale Foundation (AWF) are considering a new name for the humpback whales they study: tool carriers. Researchers know that humpback whales create “bubble nets” to hunt, but they have learned that the animals don’t just create bubble nets; they manipulate this unique resource in various ways to maximize their food intake in Alaska’s feeding grounds. This new research unravels a behavior essential to the whales’ survival and provides a compelling argument for including humpback whales among the rare animals that make and wield their own tools.
“Many animals use tools to help them find food,” explains Professor Lars Bejder, co-lead author of the study and director of MMRP, “but few actually create or adapt these tools themselves. We found that solitary humpback whales in southeastern SE) Alaska make complex bubble nets to catch krill, which are small shrimp-like creatures. These whales skillfully blow bubbles in patterns that form nets with internal rings, actively controlling details such as the number of rings, size and depth of the net. and the distance between the bubbles. This method allows them to catch up to seven times more prey in a single feeding dive without expending additional energy. This impressive behavior places humpback whales among the rare group of animals that both make and use their own tools for hunting. “
Success in hunting is key to the whales’ survival. The Southeast Alaska humpback whale population winters in Hawaii, and their year-round energy budget depends on their ability to catch sufficient food during the Southeast Alaska summer and fall. Unraveling the nuances of their carefully honed hunting techniques sheds light on how migratory humpback whales consume enough calories to cross the Pacific Ocean.
Advanced tools and partnerships are key to unraveling whale behavior
Marine mammals called cetaceans include whales, dolphins, and porpoises, and they are notoriously difficult to study. Advances in research tools make it easier to track and understand their behavior, and in this case, researchers used special tags and drones to study the whales’ movements from above and below water.
“We deployed non-invasive suction cup tags on whales and flew drones over lone humpback whales with bubble nets in Southeast Alaska, collecting data on their underwater movements,” said co-author and MMRP researcher William Gough. The tools have incredible capabilities, but honing them takes practice. Gough reflects: “Whales are a difficult group to study, requiring skill and precision to successfully tag and/or drone them.”
The logistics of working in a remote location in Southeast Alaska presented its own challenges to the research. “We are so grateful to our research partners at the Alaska Whale Foundation (AWF) for their vast knowledge of the local environment and the whales in that part of the world,” Bejder emphasizes. “This research would not have been possible without the strong collaboration with AWF.”
More insights and better management are coming
Cetaceans around the world face a plethora of threats ranging from habitat degradation, climate change, fishing and chemical and noise pollution. A quarter of the 92 known cetacean species are threatened with extinction, and there is a clear and urgent need to implement effective conservation strategies for them. The way animals hunt is key to their survival, and by understanding this essential behavior, resource managers are better able to skillfully monitor and conserve the feeding grounds that are critical to their survival.
“This little-studied foraging behavior is entirely unique to humpback whales,” notes Gough. “It’s so incredible to see these animals in their natural habitat, exhibiting behaviors that only a few people ever get to see. And it’s worth it to be able to come back to the lab, dig into the data and learn what they do.” underwater as soon as they disappear from view.”
With powerful new tools in the hands of researchers, many more exciting behavioral discoveries in cetaceans lie ahead. “This is a rich dataset that will allow us to learn even more about the physics and energetic aspects of solitary bubble nets,” says Bejder. “Data are also coming in from humpback whales exhibiting other feeding behaviors such as cooperative bubble netting, surface feeding and deep lunge feeding, allowing further exploration of the energetic landscape and fitness of this population.”
“What I find exciting is that humpback whales have devised complex tools that allow them to exploit prey collections that would otherwise not be available to them,” said Dr. Andy Szabo, executive director of AWF and co-lead of the study. “It is this behavioral flexibility and ingenuity that I hope will serve these whales well as our oceans continue to change.”
This groundbreaking work was made possible with support from Lindblad Expeditions – National Geographic Fund, the University of Hawai’i at Manoa, and a grant from the Department of Defense (DOD) Defense University Research Instrumentation Program (DURIP).
This research was conducted under a NOAA permit issued to Alaska Whale Foundation (No. 19703). All research was conducted under IACUC institutional approval.
