CURRENT STATUS AND CONSERVATION NEEDS OF DUGONGS IN SOUTHERN JAPAN

• Published in: Marine mammal science Vol. 23; no. 3; pp. 694 - 706
• Main Authors: Shirakihara, Miki, Yoshida, Hideyoshi, Yokochi, Hiroyuki, Ogawa, Hisao, Hosokawa, Taro, Higashi, Naoto, Kasuya, Toshio
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.07.2007; Blackwell
• Subjects: aerial survey; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Dugong; Dugong dugon; Dugong dugong; Fundamental and applied biological sciences. Psychology; Japan; Mammalia; Marine; Okinawa; Sea water ecosystems; snorkeling survey; Synecology; Vertebrata; Japan; Ryukyu Archipelago; Asia; ISEW, Japan, Nansei-Shoto, Okinawa Prefect., Okinawa I; ISEW, Japan, Nansei-Shoto, Okinawa Prefect., Sakishima Is; Marine environment; Status; Vertebrata; Dugong dugon; Mammalia; Sirenia; Japan; Conservation; Okinawa; dugong; Aerial survey; snorkeling survey
• ISSN: 0824-0469; 1748-7692
• DOI: 10.1111/j.1748-7692.2007.00123.x

We conducted aerial surveys of dugongs (Dugong dugon) using the line-transect method and snorkeling surveys of dugong feeding trails in 1998 and 1999 around Okinawa Island (26°30'N, 128°00'E) and the Sakishima Islands, southern Japan. A total of ten dugongs were sighted and feeding trails were confirmed in the sea grass beds off the east coast of Okinawa Island. In the Sakishima Islands, however, no dugongs were observed, and there was no evidence of feeding trails despite the existence of apparently suitable sea grass beds for feeding. The results of these surveys and other available information suggest that Okinawan dugongs represent a small, geographically isolated population. Our sightings of dugongs during the daytime, offshore of sea grass beds where feeding trails were recorded, suggest that Okinawan dugongs principally feed at night when human activities are limited. Survival of this remnant dugong population is threatened by habitat degradation and occasional entanglement mortality in fishing nets.