Conservation biology of dugong Okinawa population

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There're relatively few studies on dugong populations in Asia as far, However, Asian dugongs are endangered by development and coastal use by human activities. Further studies on dugong ecology are required for conservation of Asian dugong.In Philippines, WWF reported Philippines' dugong populations, but most of information did not based on scientific studies. There is a few researches in Palawan island. We, Japanese and Philippines' cooperative project, are studying on dugong behavior and feeding ecology of Malita, Mindanao.In China, Hinan island has been known that dugong occurred frequently. However, in our investigation almost seagrass beds on the northern coast of the island were extinct by coastal development and harbor construction. So, it was disappeared the conditions of dugong living. In Japan, It has been thought that dugong was extinct several decades ago. But, a dugong population was discovered again Okinawa island before less than 10 years. After re-discover, there were many efforts and to know dugong population and reported (Ministry of Environment. Ministry of Defense. Department of Fisheries. Etc.). Nevertheless, population size was not known exactly, about 10 by the estimation. Now, the dugong population faces to extinction due to.In our investigation of the dugong ruin, which is also called Nanazou Utaki, on the island of Simoji in the southern part of Ryukyu archipelago, Japan. We recognized fourteen stoneworks in the dugong ruin. The form of some stoneworks were similar to that of an extended flue used to capture dugong. forty six parietal bones, eight occipital bones, 22 mandibles, an atlas and a humerus were unearthed. The dugong bones had been disturbed, as the incisors and molars had been extracted from the alveolar. If neglection of the ruin and the dugong bones is continued, a great heritage will be lost. It is necessary to organaize a conservation committee.