How dolphins work with fishers in Brazil

Researchers have just confirmed what fishing together meant for Brazilians. They studied a centuries-old practice of dolphins and people fishing together in southern Brazil and learn it’s a symbiotic relationship which is now under threat.  The researchers report how bottlenose dolphins (Tursiops truncatus gephyreus) find schools of fish and herd them to the shallows, where the fishers stand and wait. The dolphins even use signals, usually by making a sudden deep dive, so the fishers know the perfect time to throw their nets. When the process works in harmony, the fishers are more successful and in turn, their nets separate individual fish that are easier prey for the dolphins. Unfortunately, the traditional practice is on the wane: artisanal fishing methods are dying out, and some fishers are turning to modern gear, such as trammel netting, that actually kills dolphins. In the research paper, the scientists propose two possible conservation actions that are targeting fishers’ behavior that could prevent the erosion of this century-old fishery, thereby safeguarding one of the last remaining cases of human–wildlife cooperation. In the video: Synchronous dolphin-fisher interaction. A typical coordinated foraging interaction between wild bottlenose dolphins and artisanal net-casting fishers in Laguna, southern Brazil (Fig. S1). Dolphins approach the coast (00’02”) herding mullet schools (00’06”) and perform a behavioral cue (00’07”) in front of the fishers who react by casting their nets (00’09”). Dolphins react to the fishers’ behavior by diving closely to the shore (00’12”) and then start emitting terminal buzz clicks (00’20”; note the audio) after the nets close and sink to the bottom, as the fishers start to retrieving their nets (00’35”).