December 15-17, 2007, Royal Phuket City Hotel, Phuket, ThailandDugongs are the only marine mammal that feeds on benthic seagrass. They are found in warm shallow waters of tropical to sub-tropical areas. Many of the dugong populations are close to extinction. We have established a new methodology to record the presence of dugongs by a passive acoustic monitoring technique using automatic underwater sound monitoring systems for dugongs in the southern part of Talibong Island, Trang, Thailand. This study described the preliminary estimation of detection rate of the dugong acoustical observation system. Visual and acoustical observation was performed simultaneously to compare the detections by each method. The results showed that almost 30% of the dugongs in the monitored area were acoustically detected. It was in the spring tide era when the maximum number of detections was obtained
