Exposure to anthropogenic sound can have a range of negative behavioral and physical effects on marine species and is of increasing ecological and regulatory concern. In particular, the response of marine mammals, and notably the family of cryptic deep-diving beaked whales, to military sonar is a timely and complex issue. To make inference on aspects of response by individual whales to noise of any type, it is critical to either measure or systematically estimate what received levels (RLs) the animal actually experienced. Various tools and techniques exist to monitor RLs and associated responses, each with advantages and disadvantages. Most behavioral response studies to date have used relatively short-term (hours to a few days), high-resolution acoustic tags that provide direct RL measurements. Because of their short duration, these tags do not allow for assessments of longer-duration baseline behavior before and following a disturbance that may tell us more about the nature of response within a broader context for tagged individuals. This paper addresses these issues and efforts to derive robust statistical RL characterizations using animal movement and fine-scale, site-specific sound propagation modeling for longer-duration tags in the context of a behavioral response study off Cape Hatteras, North Carolina. Researchers tagged nine Cuvier’s beaked whales and three short-finned pilot whales and conducted controlled exposure experiments using simulated and operational military mid-frequency active sonar. They used sound propagation modeling methods and modeled positions of individual animals to estimate RLs in four dimensions and to statistically describe uncertainty within volumes of water space where animals were predicted to occur during exposure periods.

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