Measuring the Behavior and Response to Sound of Beaked Whales Using Recording Tags

A National Oceanographic Partnership Program Award. Sponsored in part by the Strategic Environmental Research and Development Program (SERDP), Arlington, VA. The original document contains color images.

The goals of this project are to understand the reasons for, and to help reduce, the strandings of two little-known species of beaked whales related to mid-frequency navy sonars. Although they are widely distributed, these cryptic species have proven extremely difficult to study and, until recently, almost nothing was known about their subsurface behavior or vocalizations. The current project combines an advanced acoustic and orientation recording tag with methods of visual survey, photo-identification, and habitat characterization in proven productive field sites. Using these tools, the authors aim to provide a thorough characterization of the movement patterns, vocalizations, foraging styles, and preferred habitat of the two species. The resulting baseline data will greatly expand their understanding of these animals and of the deep prey on which they feed, both of which are poorly understood. Understanding of these factors is critical to designing, and evaluating the success of, any mitigation measure. Results from the study are directed at two strategies to reduce beaked whale mortality. First, with a specification of how and when these animals vocalize, it may be possible to develop systems for passive acoustic detection of beaked whales. Since beaked whales are so difficult to sight, acoustic detection is a critical method to monitor for the presence of these sensitive species before and during sonar trials. The second, longer-term strategy is to determine what factors heighten the risk of stranding and to identify opportunities to minimize these. If risk assessments continue to highlight an urgent need to define safe exposure limits for beaked whales, they propose to plan a pilot study on the behavioral responses of beaked whales to low levels of sonar-like sounds. Recognizing that research priorities may change as new data come to light, they will work with an international community of stakeholders to evaluate new opportunities.