Long-term in-situ monitoring of the Irrawaddy Dolphins (Orcaella brevirostris) in Borneo

In Borneo, to monitor the dolphin´s groups that migrate from the Semayang Lake to the Mahakam river at Pela village, the annual long-term in-situ monitoring using a stationary observatory deployed from an existing floating house was started in June 2012. Taking advantage of the floating house observation platform on the river, one SBL (Short Base Line) system which consists of a three-piece set of SSBL (Super Short Base Line) units with environmental sensors was used for the recording system. In the Mahakam river, boat traffic has been steadily increasing. Not only for understanding the trend of the dolphin´s migration but also for evaluation of increasing boat noise on their echolocation ability, basic acoustic characteristics of the dolphin´s echolocation clicks and two typical types of boat noise pulses (type A and type B) were revealed to distinguish dolphin clicks accurately from boat noise.