Observations on inshore and pelagic Dolphins on the South-Eastern Cape coast of South Africa

Abstract

The occurrence, size and seaward distribution of schools of inshore and pelagic dolphins is described for three study areas on the south-eastern Cape coast (Algoa Bay; the Tsitsikama Coastal National Park and Plettenberg Bay). Inshore dolphins {Tursiops and Sousa sp.) frequented the coastline in relatively small schools whereas pelagic dolphins {Delphinus delphis and Stenella caeruleoalba) occurred in very large schools far out to sea. Different ecological zones were used by Sousa for feeding and for social behaviour and maintenance activities. The frequency of occurrence of Sousa at Plettenberg Bay was not affected by seasonal fluctuations in sea surface temperatures. The role of dolphins as predators and their implication in the regulation of the ecosystem of the Tsitsikama Coastal National Park is discussed.