Effects of different analysis techniques and recording duty cycles on passive acoustic monitoring of killer whales

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Riera, Amalis, Ford, John K., Chapman, N. Ross
• Format: Other/Unknown Material
• Language: English
• Published: The Journal of the Acoustical Society of America 2013
• Subjects: British Columbia; Canada; Killer Whale; Killer whale
• Online Access: http://hdl.handle.net/1828/13107; https://doi.org/10.1121/1.4816552

Killer whales in British Columbia are at risk, and little is known about their winter distribution. Passive acoustic monitoring of their year-round habitat is a valuable supplemental method to traditional visual and photographic surveys. However, long-term acoustic studies of odontocetes have some limitations, including the generation of large amounts of data that require highly time-consuming processing. There is a need to develop tools and protocols to maximize the efficiency of such studies. Here, two types of analysis, real-time and long term spectral averages, were compared to assess their performance at detecting killer whale calls in long-term acoustic recordings. In addition, two different duty cycles, 1/3 and 2/3, were tested. Both the use of long term spectral averages and a lower duty cycle resulted in a decrease in call detection and positive pod identification, leading to underestimations of the amount of time the whales were present. The impact of these limitations should be considered in future killer whale acoustic surveys. A compromise between a lower resolution data processing method and a higher duty cycle is suggested for maximum methodological efficiency. This study was supported by Obra Social La Caixa and the International Council for Canadian Studies and the Species at Risk program of Fisheries and Oceans Canada. Faculty Reviewed