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CURRENT STATUS AND CONSERVATION NEEDS OF DUGONGS IN SOUTHERN JAPAN
Author(s) -
Shirakihara Miki,
Yoshida Hideyoshi,
Yokochi Hiroyuki,
Ogawa Hisao,
Hosokawa Taro,
Higashi Naoto,
Kasuya Toshio
Publication year - 2007
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2007.00123.x
Subject(s) - transect , population , threatened species , fishery , fishing , geography , habitat , ecology , biology , demography , sociology
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.