Bottlenose Dolphins, Humans Work Together To Catch Migrating Mullet in Brazil

There is a partnership between humans and dolphins in Brazil, which has been the case for over a century.

Local Fishers in Brazil Catch Mullets With The Help of Bottlenose Dolphins

Fishermen and dolphins have had an unspoken partnership for generations, which has continued for over 15 decades. Local fishers would wade into the water to catch mullet. The task is challenging, but with bottlenose dolphins' help, catching mullets is easy as pie!

The fishers will wait until the dolphins drive the fish toward the shore. When the bottlenose dolphins dive, it's the cue for the fishermen to cast their nets, according to Smithsonian magazine.

The partnership benefits humans. However, it is unclear whether dolphins also benefited from it.

Mauricio Cantor, a biologist at Oregon State University and an author of the paper, told New York Times' Asher Elbein that the human-wildlife tandem is rare at a global scale. And when it happens, humans enjoy the benefit, and nature pays the cost. However, he acknowledged that the partnership between the bottlenose dolphins and local fishers in Brazil has been going on for 150 years.

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How Effective Is The Bottlenose Dolphins, Local Fishers Partnership?

The researchers used drones, sonar, and underwater sound recording to observe what happens in the water when the fishermen cast their nets in sync with the dolphins' cues. They noticed that cetaceans increased their echolocation click creates to create a terminal buzz, indicating that they were homing in on prey. When they were not in sync, the response was less common.

The dolphins took advantage of the disoriented fish after the fishers cast and even snatched some fish directly from the nets.

The local fishermen were more successful when they worked with the bottlenose dolphins. They caught 17 times more fish and nearly four times more mullets when they synchronized their casting with the cetaceans' signals. Eighty-six percent of the 4,955 mullets caught during the study period resulted from "synchronous interactions" in which both predators acted in perfect unison.

Dolphins help fishermen by pushing the mullets toward them, generating transient high-quality patches before issuing a cue and communicating when the mullets are within reach of the fishers' nets. According to experienced fishermen, the dolphins also benefit from their partnership because they obtain food.

The study indicated that the survival rate of dolphins hunting with people was 13 percent higher than that of other dolphins. Cooperative dolphins are less likely to become entangled in unlawful fishing gear if they remain close to shore.

According to Stephanie King, a biologist at the University of Bristol in England who studies dolphin communication but was not involved in the research, the study demonstrates unequivocally that dolphins and humans are observing each other's behavior and that dolphins signal when nets should be cast. For her, it was a "truly extraordinary cooperation."

The results of the study were published in the Proceedings of the National Academy of Sciences Monday.