Marine researchers in Monterey Bay, California, captured footage of humpback whales lunge feeding alongside California sea lions, revealing that the whales exhibit a 23 percent higher feeding rate when hunting with the sea lions.
Scientists monitoring bait balls in Monterey Bay recorded interactions between humpback whales and California sea lions using video tags attached to the whales. The observations form the basis of a study published in Philosophical Transactions of the Royal Society B: Biological Sciences. During lunge feeding, whales herd fish into tight groups before propelling themselves forward to take in massive mouthfuls of water and prey, filtering out the water through their baleen plates.
Feeding Rates and Lunge Intervals During Monterey Bay Foraging
The study found that the presence of sea lions alters the foraging efficiency of the whales. Whales hunting alongside sea lions feed more frequently and take shorter breaks between their lunges.
Across 1,808 lunge-feeding events, whales foraging with sea lions exhibited a 23% higher feeding rate and a 16% shorter inter-lunge interval.
Authors of the study published in Philosophical Transactions of the Royal Society B: Biological Sciences
Despite the increased frequency, researchers observed that the presence of sea lions did not change the speed, acceleration, or manoeuvring capabilities of the humpback whales. This indicates that foraging near sea lions does not increase the energy expenditure required for each lunge, and the whales spent the same total amount of time foraging regardless of whether sea lions were present.
Hunting Strategies and Inter-Species Benefits
The advantage appears to be mutual. Researchers suggest that sea lions help bundle anchovies into more concentrated bait balls, allowing the whales to locate and capture food more quickly. Meanwhile, sea lions exploit the disruption caused by the massive filter-feeding attacks.
We observed sea lions foraging on individual, slow-moving anchovies separated from the school by humpback whale lunges.
Authors of the study published in Philosophical Transactions of the Royal Society B: Biological Sciences
The two predators utilize fundamentally different tactics. Humpback whales attempt to consume as many fish as possible in a single gulp, whereas sea lions target individual fish. Because their feeding methods differ, competition between the species remains low. Researchers noted that if the association were competitive, whales would likely show increased manoeuvring expenditure to avoid or outmanoeuvre the sea lions.
If this association were more competitive, we would expect to see increased manoeuvring expenditure of humpback whales when sea lions are present, as they work to avoid or outmanoeuvre the other species.
Authors of the study published in Philosophical Transactions of the Royal Society B: Biological Sciences
While the video footage demonstrates clear cooperation and shared benefits during hunts, questions remain about how the animals initiate these encounters. The recordings analyzed in the research were captured under NMFS permit #26602. Experts have not yet determined whether the whales actively track sea lion movements or if both predators are simply drawn independently to the same anchovy schools.
whether whales actively track sea lion activity or both predators simply converge on anchovy schools remains uncertain.
Authors of the study published in Philosophical Transactions of the Royal Society B: Biological Sciences