Remote acoustic monitoring of aquatic mammals

Organized by Graduate School of Informatics, Kyoto University ; JSPS Bangkok Liaison Office ; Japanese Society of Bio-logging Science ; Informatics Research Center for Development of Knowledge Society InfrastructureDecember 13-15, 2004, Imperial Tara Hotel, Bangkok, ThailandUnderwater ultrasonic sound of finless porpoises Neophocaena phocaenoides were monitored concurrent with visual observations in the Yangtze River, China. In a total of a 774 km cruise, 588 finless porpoises were sighted by visual observation and 44, 864 ultrasonic pulses were recorded. The acoustic monitoring system could detect presence of the finless porpoises 82% of the time. False alarms in the system occurred with a frequency of 0.9%. The high frequency acoustical observation is suggested as an effective method for field surveys of small cetaceans, which produce high frequency sonar signals