A RESIDENT POPULATION OF INDO‐PACIFIC BOTTLENOSE DOLPHINS (TURSIOPS ADUNCUS) IN AMAKUSA, WESTERN KYUSHU, JAPAN

Abstract

Residency patterns and population size were examined for Indo‐Pacific bottlenose dolphins (Tursiops aduncus) in the coastal waters of Amakusa‐Shimoshima Island, western Kyushu, Japan, from summer 1994 to fall 1998. A total of 203 individuals were identified. The number of newly identified individuals barely increased after the first 1.5 yr. The identified individuals in one season were frequently resighted with percentages of mostly over 60% during the subsequent seasons. Most of the dolphins off Amakusa were yearround residents, although the total range of their habitat was unknown. The population size estimated by the mark‐recapture technique was 218 individuals with a CV of 5.41% in 1995–1997. The group commonly consisted of more than 100 individuals. The large group size was thought to be a response to feeding on schooling fishes.

Capture-mark-recapture modelling suggests an Endangered status for the Mayotte Island (eastern Africa) population of Indo-Pacific bottlenose dolphins

“…Around the Solomon Islands, bottlenose dolphins are threatened by live captures (Reeves & Brownell 2009). In Amakusa, western Kyushu, Japan, Indo-Pacific bottlenose dolphins appear to be threatened by dolphin-watching operations (Shirakihara et al 2002).…”

Long-Distance Movements of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) and Habitat Preference of Two Species of Bottlenose Dolphins in Eastern Kyushu, Japan

“…Boat positions (within 100 m from the group) were automatically logged using a GARMIM eTrex 33 indicate the positions of "small coastal g roups" and "other g roups", respectiv ely . (Shinohara, 1998;Shirakihara et al, 2002;Fujita, 2003;Kogi et al, 2004;Nanbu et al, 2006;Mori & Yoshioka, 2010;Morisaka et al, 2010;Funasaka et al, 2011). Dotted line indicates the prefectural boundary; KS = Kyushu; SK = Shikoku; and ★ = Tozaki.…”

“…No records of Indo-Pacific bottlenose dolphins were previously reported in that region, despite the presence of resident individuals of this species in both western and southern Kyushu (Shirakihara et al, 2002;Nanbu et al, 2006). Surveys were required to determine whether the dolphins were Indo-Pacific bottlenose dolphins or other dolphin species.…”

“…Individual Indo-Pacific bottlenose dolphins were identified using natural marks along the dorsal fin (Würsig & Jefferson, 1990). Photographs of the fin were compared to the photo-identification catalog of the Amakusa population (which contains 300 individuals) created previously by the authors (Shirakihara et al, 2002;Shirakihara & Shirakihara, in press) and to those of the Kagoshima Bay population (which contains 25 individuals), created by Nanbu et al (2006). The distance between Amakusa and Oita, when measured along the coast, was about 700 km.…”

“…Small-isolated populations of Indo-Pacific bottlenose dolphins are found in Japanese waters (Shinohara, 1998;Shirakihara et al, 2002;Kogi et al, 2004;Nanbu et al, 2006;Mori & Yoshioka, 2009;Funasaka et al, 2011; Figure 1). Geographic differences in whistle acoustic parameters and genetic differentiations were found among populations (Hayano et al, 2004;Morisaka et al, 2005).…”