"Many animals use tools to help them find food," stated Professor Lars Bejder, co-lead author of the study and Director of MMRP. "But very few actually create or modify these tools themselves. We discovered that solitary humpback whales in southeast (SE) Alaska craft complex bubble nets to catch krill, which are tiny shrimp-like creatures. These whales skillfully blow bubbles in patterns that form nets with internal rings, actively controlling details like the number of rings, the size and depth of the net, and the spacing between bubbles. This method lets them capture up to seven times more prey in a single feeding dive without using extra energy. This impressive behavior places humpback whales among the rare group of animals that both make and use their own tools for hunting."
The success of this hunting strategy is critical for the whales' survival. The humpback population in SE Alaska migrates to Hawai?i for the winter, and their energy reserves for the entire year depend on the food they capture during the summer and fall in SE Alaska. Understanding the intricacies of their hunting methods provides valuable insight into how these migratory whales acquire the necessary calories to complete their long journey across the Pacific Ocean.
Innovative Tools and Collaboration Unveil Whale Behavior
Studying marine mammals like whales, dolphins, and porpoises, which belong to the cetacean family, presents significant challenges due to their elusive nature. However, advancements in research technology have made it easier to monitor and comprehend their behaviors. In this study, researchers utilized specialized tags and drones to observe the whales' movements both above and below the water.
"We deployed non-invasive suction-cup tags on whales and flew drones over solitary bubble-netting humpback whales in SE Alaska, collecting data on their underwater movements," shared co-author and MMRP researcher William Gough. The tools have incredible capability, but honing them takes practice. Gough reflected, "Whales are a difficult group to study, requiring skill and precision to successfully tag and/or drone them."
Conducting research in the remote areas of SE Alaska also posed logistical challenges. "We are so grateful to our research partners at the Alaska Whale Foundation (AWF) for their immense knowledge of the local area and the whales in that part of the world," emphasized Bejder. "This research would not have been possible without the strong collaborative effort with AWF."
Future Insights and Enhanced Conservation Strategies
Cetaceans face numerous threats worldwide, ranging from habitat destruction and climate change to fisheries and pollution. With one-quarter of the 92 known cetacean species at risk of extinction, it is imperative to develop effective conservation strategies. Understanding how these animals hunt is crucial to their survival, and this knowledge equips resource managers with the tools needed to protect the vital feeding grounds on which these animals rely.
"This little-studied foraging behavior is wholly unique to humpback whales," noted Gough. "It's so incredible to see these animals in their natural habitat, performing behaviors that only a few people ever get to see. And it's rewarding to be able to come back to the lab, dive into the data, and learn about what they're doing underwater once they disappear from view."
With these powerful new tools in hand, researchers anticipate many more exciting discoveries regarding cetacean behavior. "This is a rich dataset that will allow us to learn even more about the physics and energetics of solitary bubble-netting," shared Bejder. "There is also data coming in from humpback whales performing other feeding behaviors, such as cooperative bubble-netting, surface feeding, and deep lunge feeding, allowing for further exploration of this population's energetic landscape and fitness."
"What I find exciting is that humpbacks have come up with complex tools allowing them to exploit prey aggregations that otherwise would be unavailable to them," said Dr. Andy Szabo, AWF Executive Director and study co-lead. "It is this behavioral flexibility and ingenuity that I hope will serve these whales well as our oceans continue to change."
Related Links
Marine Mammal Research Program
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