In the resort town of Laguna in southern Brazil: a pod of bottlenose dolphins has developed a cooperative technique to herd mullet towards local fishermen. The dolphins drive a school of fish towards the men, who cannot see the fish in the muddy, shallow water. Relying on the dolphins’ cue, a conspicuous roll just out of net range, the fishermen cast their nets. Those mullet missed by the fishing nets are momentarily disoriented, making them easy food for the well-positioned dolphins.
The dolphins were not trained for this behavior — in fact, the activity is initiated and led by the dolphins. The fishermen don’t cast their nets until signaled to do so by their aquatic partners. Town records indicate that this almost-daily collaborative partnership dates back to at least 1847.
As cited in the interesting paper, “Dolphins and the Question of Personhood”, marine researchers consider this further evidence that dolphins make conscious choices and thus should be considered sentient persons.