Habitat Use by Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in Amakusa, Japan

Abstract: Habitat use by Indo-Pacific bottlenose dolphins (Tursiops aduncus) with a maximum group size > 100 individuals in the northern coastal waters of Amakusa-Shimoshima Island, western Kyushu, Japan, was examined for 51 d between October 1996 and December 1997. Systematic behavioral sampling and theodolite tracking techniques were used to collect data. The core habitat area (CHA), defined as the 50% kernel density estimate, was located in the northern coastal area near Tsuji Island. Occurrences of dolphin groups in the CHA were higher during ebb and low tides. A group behavior that corresponded to resting was seen around the CHA, while both traveling and feeding were seen in a wider area outside of the CHA. Dolphin groups were found in the eastern area of the CHA during morning hours, and the groups spent more time in the CHA in the afternoon hours. Unidirectional movements, mainly toward western offshore waters, occurred after 1600 h. Numerous dolphin-watching boats are attracted to the CHA. Managing policies and enforcement are required for the local dolphin-watching industry.
Key Words: Indo-Pacific bottlenose dolphin, Tursiops aduncus, cetacean, theodolite, habitat, dolphin tourism
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.2.2017.127
Page Numbers: 127-138

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