Abstract
A bstract Mark‐recapture analyses were performed on photo‐identification data for Indo‐Pacific humpback dolphins ( Sousa chinensis ) inhabiting Algoa Bay, on the Eastern Cape coast of South Africa. Boat‐based photo‐ID surveys were undertaken between May 1991 and May 1994. The rate of discovery of newly identified dolphins, distribution of sightings and frequency of resightings of known individuals indicate a high level of seasonal immigration of humpback dolphins into, and emigration from, the Algoa Bay region in summer. Consequently, humpback dolphins from Algoa Bay appear to be part of a substantially larger population that uses a considerable length of the coastal zone. The minimum population size is estimated to be about 466 dolphins.