title: Source levels of dugong (Dugong dugon) vocalizations recorded in Shark Bay.
abstract: Dugongs (Dugong dugon) spend significant time in shallow, turbid waters and are often active at night, conditions which are not conducive to visual cues. In part, as a result, dugongs vocalize to gain or pass information. Passive acoustic recording is a useful tool for remote detection of vocal marine animals, but its application to dugongs has been little explored compared with other mammals. Aerial surveys, often used to monitor dugong distribution and abundance, are not always financially or logistically viable and involve inherent availability and perception bias considerations. Passive acoustic monitoring is also subject to sampling biases and a first step to identifying these biases and understanding the detection or communication range of animal calls is to determine call source level. In March 2012, four dugongs were fitted with satellite tags in Shark Bay, Western Australia by the Department of Environment and Conservation. During this, acoustic recordings were taken at 5.1 m range. Source levels for each of five call types (two types of chirp, bark, squeak, and quack) were estimated, assuming spherical spreading as the transmission loss. Mean source levels for these call types were 139 (n = 19), 135 (12), 142 (2), 158 (1), and 136 (9) dB re 1 μPa at 1 m, respectively.
authors: Centre for Marine Science and Technology, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia. m.parsons@cmst.curtin.edu.au
authors: Miles J G
authors: MJ
authors: Parsons
authors: Dave
authors: D
authors: Holley
authors: Robert D
authors: RD
authors: McCauley
mesh_terms: D000162:Acoustics; D000818:Animals; D015982:Bias; D020454:Dugong / Q000502:physiology* / Q000523:psychology; D004784:Environmental Monitoring / Q000379:methods*; D008297:Male; D008386:Marine Biology / Q000379:methods*; D009038:Motion; D009792:Oceans and Seas; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014828:Vocalization, Animal; D014904:Western Australia