Facts on Bottlenose Dolphins.
There are three dolphin species seen in Plettenberg Bay on a regular basis. They are Bottlenose dolphins (Tursiops aduncus), Humpback dolphins (Sousa chinensis) and Common dolphins (Delphinus sp). The species seen most frequently is the Bottlenose dolphin. Bottlenose dolphins got the name from their short beak and can grow up to 2.5m in length and weigh up to 275kg. They can live to 40 years or older and the average group size is 20-80 animals, however groups of 200-500 have been recorded in Plettenberg Bay. Bottlenose dolphins are protected in South African waters and are listed as least concerned on the red list.
Bottlenose dolphins are found all over the world. There are currently two recognised species (Tursiops aduncas and Tursiops truncatus). T. truncatus is a large offshore species while T. aduncus is a small inshore species that live in waters shallower than 50m. They feed mainly on small fish, squid and crustaceans.
Although not an endangered species, there are a number of human induced threats to Bottlenose dolphins. These threats come in various forms, from entanglement and drowning in fishing and shark exclusion nets to a build-up of toxins in their bodies from agricultural run-off and pollution. Their natural enemies are sharks and Orcas (Killer whales). Bottlenose dolphins are the most commonly caught species for aquariums.
Like most dolphin species, Bottlenose dolphins have a matriarch (female leader). The females tend to stay together throughout their lives, whereas the males leave their mother’s pod between 3-6 years of age, form bachelor pods that move between other, unrelated, female pods in order to reproduce.
In Plettenberg Bay Bottlenose dolphins are seen all year round. A study from 2005 estimated there are between 3,000-10,000 Bottlenose dolphins that visit Plettenberg Bay in one year. In 2012 it was concluded that they come to the bay in a seasonal pattern, so the animals seen now in winter will not necessarily be seen in summer, but only next winter again.