Dose-response relationships for the onset of avoidance of sonar by free-ranging killer whales

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Miller, Patrick, Antunes, Ricardo Nuno, Wensveen, Paulus Jacobus, Samarra, Filipa Isabel Pereira, Alves, Ana Catarina De Carvalho, Tyack, Peter Lloyd, Kvadsheim, Petter H., Kleivane, Lars, Lam, Frans-Peter A., Ainslie, Michael A., Thomas, Len
• Other Authors: Office of Naval Research, University of St Andrews.School of Biology, University of St Andrews.Marine Alliance for Science & Technology Scotland, University of St Andrews.Scottish Oceans Institute, University of St Andrews.Institute of Behavioural and Neural Sciences, University of St Andrews.Centre for Social Learning & Cognitive Evolution, University of St Andrews.Bioacoustics group, University of St Andrews.Sea Mammal Research Unit, University of St Andrews.Sound Tags Group, University of St Andrews.Statistics, University of St Andrews.Centre for Research into Ecological & Environmental Modelling
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: QH301 Biology; V Naval Science (General); GC Oceanography; BDC; R2C; SDG 3 - Good Health and Well-being; QH301; V1; GC; Killer Whale; Killer whale
• Online Access: https://hdl.handle.net/10023/5092; https://doi.org/10.1121/1.4861346

The authors acknowledge the support of the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) in the completion of this study. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. Eight experimentally controlled exposures to 1−2 kHz or 6−7 kHz sonar signals were conducted with four killer whale groups. The source level and proximity of the source were increased during each exposure in order to reveal response thresholds. Detailed inspection of movements during each exposure session revealed sustained changes in speed and travel direction judged to be avoidance responses during six of eight sessions. Following methods developed for Phase-I clinical trials in human medicine, response thresholds ranging from 94 to 164 dB re 1 μPa received sound pressure level (SPL) were fitted to Bayesian dose-response functions. Thresholds did not consistently differ by sonar frequency or whether a group had previously been exposed, with a mean SPL response threshold of 142 ± 15 dB (mean ± s.d.). High levels of between- and within-individual variability were identified, indicating that thresholds depended upon other undefined contextual variables. The dose-response functions indicate that some killer whales started to avoid sonar at received SPL below thresholds assumed by the U.S. Navy. The predicted extent of habitat over which avoidance reactions occur depends upon whether whales responded to proximity or received SPL of the sonar or both, but was large enough to raise concerns about biological consequences to the whales. Peer reviewed