Tracking trials of echolocating finless porpoise by two stationary passive acoustic monitoring systems

Abstract

This study showed the preliminary results of two-dimensional localization of echolocating finless porpoises by two stereo acoustic data loggers, A-tags. We conducted passive acoustic observation from an anchored fishing boat using two separated A-tags. Five echolocating porpoises were tracked during a 1.5-hour monitoring. The estimated swimming speeds of the porpoises matched the previous study, which were measured using bio-logging technique. At least one track of porpoises, however, was considered to contain false localization because the swimming speed was faster than the maximum speed of porpoises. Stationary acoustic monitoring has a limited observation range compared to a moving platform. But it has advantages to be able to easily measure the swimming speed and observe under water movement of underwater porpoises. In the future work, it is necessary to observe wild behavior of this species and evaluate the accuracy of the localization method by using larger sample size.