Naval sonar disrupts foraging in humpback whales

• Published in: Marine Ecology Progress Series
• Main Authors: Silve, Lise Doksæter, Wensveen, Paul Jacobus, Kvadsheim, Petter Helgevold, Lam, Frans-Peter Alexander, Visser, Fleur, Cure, Charlotte, Harris, Catriona M., Tyack, Peter Lloyd, Miller, Patrick James O'malley
• Other Authors: Institute of Marine Research Bergen (IMR), University of Bergen (UiB), University of St Andrews Scotland, Norwegian Defence Research Establishment (FFI), The Netherlands Organisation for Applied Scientific Research (TNO), Kelp Marine Research, parent, Unité Mixte de Recherche en Acoustique Environnementale (UMRAE), Université de Lyon-Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema)-Université Gustave Eiffel
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: ACLI; CEREMA; IMPACT; INTERNATIONAL; SONAR; [SDE]Environmental Sciences; Humpback Whale
• Online Access: https://hal.science/hal-02915542; https://doi.org/10.3354/meps11969

Modern long-range naval sonars are a potential disturbance for marine mammalsand can cause disruption of feeding in cetaceans. We examined the lunge-feeding behaviour ofhumpback whales Megaptera novaeangliaebefore, during and after controlled exposure experi-ments with naval sonar by use of acoustic and motion sensor archival tags attached to each animal.Lunge-feeding by humpback whales entails a strong acceleration to increase speed before engulf-ing a large volume of prey-laden water, which can be identified by an acoustic signature charac-terized by a few seconds of high-level flow-noise followed by a rapid reduction, coinciding with apeak in animal acceleration. Over 2 successive seasons, 13 humpback whales were tagged. Allwere subject to a no-sonar control exposure, and 12 whales were exposed to 2 consecutive sonarexposure sessions, with 1 h between sessions. The first sonar session resulted in an average 68%reduction in lunge rate during exposure compared to pre-exposure, and this reduction was signif-icantly greater than any changes observed during the no-sonar control. During the second sonarsession, reduction in lunge rate was 66% during sonar exposure compared to the pre-exposurelevel, but was not significant compared to the no-sonar control, likely due to a larger inter-individ-ual variability because some individuals appeared to have habituated whereas others had not.Our results indicate that naval sonars operating near humpback whale feeding grounds may leadto reduced foraging and negative impacts on energy balance