Henderson E Elizabeth, Smith Michael H, Gassmann Martin, Wiggins Sean M, Douglas Annie B, Hildebrand John A
Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093.
Gray Whales Count, 1 Fellowship Circle, Santa Barbara, California 93109.
J Acoust Soc Am. 2014 Oct;136(4):2003-14. doi: 10.1121/1.4895681.
Opportunistic observations of behavioral responses by delphinids to incidental mid-frequency active (MFA) sonar were recorded in the Southern California Bight from 2004 through 2008 using visual focal follows, static hydrophones, and autonomous recorders. Sound pressure levels were calculated between 2 and 8 kHz. Surface behavioral responses were observed in 26 groups from at least three species of 46 groups out of five species encountered during MFA sonar incidents. Responses included changes in behavioral state or direction of travel, changes in vocalization rates and call intensity, or a lack of vocalizations while MFA sonar occurred. However, 46% of focal groups not exposed to sonar also changed their behavior, and 43% of focal groups exposed to sonar did not change their behavior. Mean peak sound pressure levels when a behavioral response occurred were around 122 dB re: 1 μPa. Acoustic localizations of dolphin groups exhibiting a response gave insight into nighttime movement patterns and provided evidence that impacts of sonar may be mediated by behavioral state. The lack of response in some cases may indicate a tolerance of or habituation to MFA sonar by local populations; however, the responses that occur at lower received levels may point to some sensitization as well.
2004年至2008年期间，在南加利福尼亚湾，利用视觉焦点跟踪、固定水听器和自主记录器，对海豚科动物对中频主动声呐（MFA）的偶然行为反应进行了机会性观察。计算了2至8千赫之间的声压级。在MFA声呐事件中遇到的五个物种中的46个群体中，至少有三个物种的26个群体观察到了水面行为反应。反应包括行为状态或行进方向的改变、发声率和叫声强度的改变，或者在MFA声呐出现时不发声。然而，46%未暴露于声呐的焦点群体也改变了它们的行为，43%暴露于声呐的焦点群体没有改变它们的行为。出现行为反应时的平均峰值声压级约为122分贝（参考值：1微帕）。对表现出反应的海豚群体的声学定位有助于了解夜间运动模式，并提供了声呐影响可能由行为状态介导的证据。在某些情况下缺乏反应可能表明当地种群对MFA声呐具有耐受性或适应性；然而，在较低接收水平下出现的反应也可能表明存在某种敏感化。
