Data from: First direct measurements of behavioural responses by Cuvier’s beaked whales to mid-frequency active sonar

Most marine mammal strandings coincident with naval sonar exercises have involved Cuvier’s beaked whales (Ziphius cavirostris). We recorded acoustic and animal movement data on two tagged Ziphius and obtained the first direct measurements of behavioural responses of this species to mid-frequency active (MFA) sonar signals. Each recording included a 30-minute playback (one 1.6-s simulated MFA sonar signal repeated every 25 s); one whale was also incidentally exposed to MFA sonar from distant naval exercises. Whales responded strongly to playbacks at low received levels (89-127 dB re1µPa): after ceasing normal fluking and echolocation, they swam rapidly, silently away, extending both dive duration and subsequent non-foraging interval. Distant sonar exercises (78-106 dB re 1 µPa) did not elicit such responses, suggesting that context may moderate reactions. The observed responses to playback occurred at received levels well below current regulatory thresholds; equivalent responses to operational sonars could elevate stranding risk and reduce foraging efficiency.

多数与海军声呐演习相关的海洋哺乳动物搁浅事件，均涉及柯氏喙鲸（Ziphius cavirostris）。本研究对2只佩戴追踪标签的柯氏喙鲸开展了声学与动物运动数据采集，首次直接测得该物种对中频主动声呐（mid-frequency active, MFA）信号的行为反应。每次数据采集包含30分钟的声呐回放实验：每25秒重复播放一次时长1.6秒的模拟中频主动声呐信号；其中1只柯氏喙鲸还意外接触到了来自远端海军演习的中频主动声呐信号。
柯氏喙鲸在较低接收声级（89~127 dB re1µPa）下对声呐回放产生了强烈反应：在停止正常的尾鳍拍水与回声定位行为后，它们会快速静默地远离声源，同时延长了潜水时长与后续的非觅食间隔期。而远端海军演习产生的声呐（接收声级78~106 dB re1µPa）并未引发此类反应，这表明环境背景可能会调节动物的行为反应。
本研究观测到的声呐回放反应，其发生时的接收声级远低于当前的监管阈值；若现役军用声呐引发同等反应，则可能会提升搁浅风险并降低觅食效率。