title: High thresholds for avoidance of sonar by free-ranging long-finned pilot whales (Globicephala melas).
abstract: The potential effects of exposing marine mammals to military sonar is a current concern. Dose-response relationships are useful for predicting potential environmental impacts of specific operations. To reveal behavioral response thresholds of exposure to sonar, we conducted 18 exposure/control approaches to 6 long-finned pilot whales. Source level and proximity of sonar transmitting one of two frequency bands (1-2 kHz and 6-7 kHz) were increased during exposure sessions. The 2-dimensional movement tracks were analyzed using a changepoint method to identify the avoidance response thresholds which were used to estimate dose-response relationships. No support for an effect of sonar frequency or previous exposures on the probability of response was found. Estimated response thresholds at which 50% of population show avoidance (SPLmax=170 dB re 1 μPa, SELcum=173 dB re 1 μPa(2) s) were higher than previously found for other cetaceans. The US Navy currently uses a generic dose-response relationship to predict the responses of cetaceans to naval active sonar, which has been found to underestimate behavioural impacts on killer whales and beaked whales. The navy curve appears to match more closely our results with long-finned pilot whales, though it might underestimate the probability of avoidance for pilot-whales at long distances from sonar sources.
authors.affiliation: Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK. Electronic address: rna@st-andrews.ac.uk.
authors.forename: R
authors.initials: R
authors.lastname: Antunes
authors.affiliation: Norwegian Defence Research Establishment, Maritime Systems, N-3191 Horten, Norway.
authors.forename: P H
authors.initials: PH
authors.lastname: Kvadsheim
authors.affiliation: Acoustics & Sonar Research Group, Netherlands Organization for Applied Scientific Research (TNO), Oude Waalsdorperweg 63, 2597 AK The Hague, The Netherlands.
authors.forename: F P A
authors.initials: FP
authors.lastname: Lam
authors.affiliation: Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK; Biology Department, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 94305, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Tyack
authors.affiliation: CREEM Centre for Research into Ecological and Environmental Modelling, University of St. Andrews, St. Andrews, Scotland KY16 9LZ, UK.
authors.forename: L
authors.initials: L
authors.lastname: Thomas
authors.affiliation: Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Wensveen
authors.affiliation: Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK.
authors.forename: P J O
authors.initials: PJ
authors.lastname: Miller
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D009622:Noise / Q000009:adverse effects*; D050686:Whales, Pilot / Q000523:psychology*
keywords: Dose–response; Marine mammals; Noise; Pilot-whales; Sonar