The importance of considering whales and dolphins as individuals, each with their own personalities, experiences and strategies has been highlighted by a study of interactions between dolphins and fishermen off the beaches of Laguna, in Brazil published in the journal Animal Behaviour. At various locations in Laguna, between 10 to 20 dolphins will herd fish to where the men wait in a line with their nets. The reward – fish!
Laguna is one of only three or four locations in the world where such human-dolphin cooperation is known to occur. The fishermen watch for the approaching dorsal fins of dolphins herding in schools of fish, then cast their nets in response to signals such as a tail slapped against the water.
The dolphins mostly fell into two groups: cooperators, that spent most of their time hunting with the fishermen, and non-cooperators, those hunting on their own or with other dolphins and rarely interacting with the fishermen. For those dolphins who did co-operate and help the fishermen, a rich buffet was the reward without the need to travel far.
Researchers at the Federal University of Santa Catarina in Brazil wondered why all the dolphins didn’t take advantage of this supply of food and think that working with fishermen is a skill that they dolphins must learn through practice and observation, and that not all the dolphins know how to do it. Also, it seems that there is only room for a few dolphins to work with fishermen at a time, and the researchers have noted a few occasions when dolphins seemed to be defending fishing sites from one another, or that one dolphin or a pair of dolphins may move into a cooperative fishing site as soon as another group leaves.
Find out more about how smart dolphin are here