New Research Alert: Humpback Whales Manufacture Bubble-nets as Tools

[SITKA, ALASKA, August 21, 2024] - In a groundbreaking study published today in Royal Society Open Science, scientists from the Alaska Whale Foundation (AWF) and the Marine Mammal Research Program (MMRP; University of Hawaiʻi at Mānoa) describe humpback whale tool use in new depth. Their findings position humpbacks among the rarified animals that manufacture and use complex tools, and shine light on how this behavior may benefit this intelligent marine mammal species in the face of climate change. 

Humpback whales are well known for the bubble-net tools they manufacture while foraging throughout the world’s oceans. Until now, scientists had not explored the structure of these nets or how their use benefits the whales. Co-led by Drs. Andy Szabo (Executive Director, AWF) and Lars Bejder (Director, MMRP), the research team coupled long-term monitoring efforts with high-tech tools - including on-animal suction-cup camera tags and drones - to address these issues and to consider why, despite the benefits they identified, this behavior remains comparatively rare. The team found that the whales can modify the nets’ size, shape, number of rings, and ‘mesh size’ to create complex structures that effectively corral and concentrate their krill prey. 

“Once we realized that the whales could use these tools to concentrate the krill by, on average, sevenfold, which ultimately means far fewer mouthfuls to get the same amount of food, we began to question ‘why don’t they always use bubble-nets?’” says Dr. Andy Szabo, AWF Executive Director and study co-lead. It turns out that there is a trade-off: although nets clearly provide benefits, it takes a lot of time to produce them, so under most conditions it appears the whales can do as well - or better - without them. However, when the whales encounter prey in low density, they can use these tools to concentrate them enough to make them profitable. “What I find exciting,” says Dr. Szabo, “is that humpbacks have come up with complex tools allowing them to exploit prey aggregations that otherwise would be unavailable to them. It is this behavioral flexibility and ingenuity that I hope will serve these whales well as our oceans continue to change.” 

With powerful new tools in the researchersʻ hands, many more exciting cetacean behavioral discoveries lie on the horizon. “This is a rich dataset that will allow us to learn even more about the physics and energetics of solitary bubble-netting,” shares Dr. Lars Bejder, Director of MMRP and study co-lead. “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.”

This groundbreaking work was made possible with support from Lindblad Expeditions-National Geographic Fund, the University of Hawaiʻi at Mānoa, and a Department of Defense (DOD) Defense University Research Instrumentation Program (DURIP) grant. 

This study was conducted under a NOAA permit issued to Alaska Whale Foundation (no. 19703). All research was conducted under institution IACUC approvals.

Read the publication open-access here:

https://royalsocietypublishing.org/doi/10.1098/rsos.240328