Detection of beaked whale clicks in underwater noise recordings

Abstract

Combined visual and acoustic surveys for beaked whales (BWs) were carried out between 15th August and 25th September 2008, and between 8 July and 2 August 2009 in an area of the Coral Sea used for naval exercises. These surveys were part of a collaborative project between the Universities of Sydney, Queensland, Curtin University and the Defence Science and Technology Organisation (DSTO) aimed at trialling methods for detecting BWs, and determining their distribution across the exercise area. One of the methods trialled in the survey was the deployment of high-frequency (HF) noise loggers on drift moorings for 2-3 days at a time. A HF noise logger was developed by the Centre for Marine Science and Technology (CMST) at Curtin University specifically for this project. The HF noise loggers were deployed autonomously on drift moorings for durations ranging from 1 hour to over 3 days during the Coral Sea surveys. Over the two surveys, there were 14 deployments in the survey area, which combined recorded 225 hours of underwater sound sampled at 192 ksps. Thousands of clicks that are likely to be BW echolocation clicks were detected in the HF noise logger recordings.