Marine Mammals and Low-Frequency Sound: Progress Since 1994 (2000)

Summary: In 1994, the Defense Advanced Research Projects Agency requested that the NRC evaluate the results of the Acoustic Thermometry of Ocean Climate’s Marine Mammal Research Program, which was designed to monitor the effects of the Acoustic Thermometry of Ocean Climate experiment’s transmissions on marine mammals. This report updates an earlier report, including the issue of acoustic. The 1994 amendments to the Marine Mammal Protection Act (MMPA) changed the legal definitions of marine mammal “harassment” as applied to scientific use of sound in the ocean. If MMPA is to be implemented responsibly, however, additional changes should be made to the act and accompanying regulations. Unfortunately, few data are available to regulators regarding ambient noise levels in the ocean and the relative importance of different sources in contributing to the cumulative human-generated noise. Our understanding of how marine mammals react to natural and humanmade sound is rudimentary. The actions recommended in this report could result in significant advances in knowledge and better regulation of human activities that might be harmful to marine mammals.