Reported by 1 source

The short version

  • Researchers observed a male bottlenose dolphin repeatedly chasing bigeye trevally until they vomited, then consuming the regurgitated food.
  • The behavior represents one of the first detailed accounts of kleptoparasitism in cetaceans, challenging assumptions about typical dolphin foraging methods.
  • Scientists debate whether the dolphin intentionally targets full-stomached fish using echolocation or if the behavior is opportunistic.

A study published in Ecology and Evolution details an unusual foraging technique employed by a common bottlenose dolphin off the coast of Australia. The animal, known locally as Bubbles, does not pursue fish to consume them directly. Instead, he chases individual bigeye trevally until they regurgitate their stomach contents, which he then eats. This behavior offers scientists a rare window into kleptoparasitism, or food stealing, within cetaceans, a group that includes dolphins, whales, and porpoises.

The research team conducted observations between June 2021 and October 2025 near Lady Elliot Island, a coral cay located at the southern end of the Great Barrier Reef. Using GoPro cameras, marine scientists recorded twenty distinct foraging attempts by the adult male dolphin. In eleven of these instances, Bubbles successfully consumed food that had been vomited by the trevally he was pursuing. During a single thirty-minute session, the dolphin performed up to ten such chases, indicating a consistent and repeated strategy rather than a one-time occurrence.

News Journal

Before initiating a chase, Bubbles exhibited specific behaviors that suggest deliberate targeting. He produced clicking sounds and twisted his head from side to side while swimming near schools of fish. Researchers hypothesize that he may be using echolocation to assess the internal state of potential targets. Echolocation allows dolphins to detect subtle differences in shape, size, and structure, which could enable Bubbles to identify which trevally have full stomachs and are therefore likely to yield a substantial meal if pressured.

Once Bubbles selected a target, he engaged in repetitive clicking and low-frequency vocalizations while pursuing the fish. Scientists propose two potential explanations for why the trevally regurgitate during these encounters. One theory is that the dolphin’s vocalizations and physical pursuit frighten the fish into vomiting. An alternative possibility is that the fish use regurgitation as a defensive decoy, ejecting their stomach contents to distract the predator and increase their chances of escape.

The motivation behind Bubbles’ preference for regurgitated food remains uncertain. One hypothesis suggests that the dolphin initially attempted to eat the fish directly but learned to exploit the easier option after observing a successful regurgitation event. Another perspective, offered by marine biologists not involved in the study, is that bigeye trevally are large and difficult to capture and consume. Eating pre-digested food may require less energy and time than hunting and swallowing whole fish, making it an efficient foraging strategy.

Despite the compelling video evidence, some experts caution against attributing complex intent to the dolphin’s actions. Jason Bruck, a marine biologist at Stephen F. Austin State University, noted that while the repeated nature of the behavior suggests more than simple opportunism, it is difficult to prove that Bubbles deliberately harasses fish with the specific expectation of regurgitation. The distinction between learned opportunistic feeding and intentional kleptoparasitism remains a subject of scientific debate.

Kleptoparasitism is well-documented in birds, such as frigatebirds, which are known for stealing food from other species. However, documenting this behavior in cetaceans has proven challenging due to the difficulty of observing underwater interactions over extended periods. Previous reports of food theft in dolphins are rare, with one notable example involving a dolphin stealing fish from cormorants. The current study suggests that unconventional foraging tactics may be more common than previously recorded but remain underreported due to observational limitations.

The researchers emphasize the need for advanced monitoring technologies to better understand cetacean behavior. Combining underwater surveys with drone technology could provide longer-term and more comprehensive data on how dolphins interact with their environment and prey. As marine science continues to evolve, cases like Bubbles’ may reveal a broader spectrum of adaptive strategies among marine mammals that were previously overlooked or misunderstood.

Sources behind this briefing

Go to the original reporting

  • Smithsonian Magazine↗Meet Bubbles, a Dolphin in Australia That Chases Fish Until They Barf—Then Eats Their Upchucked Meals