Bottlenose dolphins in the waterways around Savannah, Georgia interact with people in different ways. Some follow shrimp trawlers, feeding on the fish that have been caught in or stirred up by the nets, or discarded as bycatch. Others do not engage in this behaviour.
To find out if such behaviour resulted in any social ramifications, researchers from Savannah State University in the US observed the bottlenose dolphins in the estuarine waterways for three consecutive summers, using photo-identification surveys to identify 137 dolphins. They sought to find out whether the dolphins begged or followed trawlers, and how often individual dolphins were together.
They discovered that the dolphins can be grouped into six social clusters; three which followed shrimp trawlers and three which did not. They also discovered that the begging and non-begging dolphins were spread across the clusters, thereby suggesting that the behaviour of foraging behind shrimp trawlers may be a socially-learnt behaviour.
The researchers recently published their findings in the PLOS ONE journal. Co-author Robin Perrtree said, “Bottlenose dolphins interact with humans, which puts them at risk of injury or death. Risky behaviours, such as begging at recreational boats and interacting with shrimp trawls, are not the same and should not be treated as comparable by researchers and managers.”