The Occurrence and Individual Identification Study of Indo-Pacific Bottlenose DolphinsTursiops aduncusin the Waters Around Amami Oshima Island, Southern Japan: A preliminary Report

Abstract

Abstract. Surveys for the occurrence, distribution, and individual identification of Indo-Pacific bottlenose dolphins Tursiops aduncus were conducted around Amami Oshima Island, Kagoshima Prefecture, Japan from 2007 to 2013. The dolphins were primarily distributed in the areas where the survey effort was concentrated, particularly in Oshima Strait and on the western coast of the Island. In total, 33 groups of dolphins were encountered with a median group size of 8 (range: 1–50 individuals). The group size in Oshima Strait was significantly smaller than that recorded off the western coast. A total of 100 individuals were identified from photographs taken by the survey cruise and local residents with the cumulative number of identified individuals increasing over time and with no indication of saturation being reached. Thus, the population size of Indo-Pacific bottlenose dolphins in the waters around Amami Oshima Island was probably larger than that indicated by the present study; hence, photo-identificatio...