The public’s interest in the impact of human-generated ocean noise on marine animals has greatly increased. Concerns include whether human-generated sounds may interfere with the normal use of sound by the marine animals or whether the human-generated sounds may cause the animals physical harm. At issue is whether the human-generated sounds affect the ability of marine animals to pursue their normal activities and the long-term ability of these animals to survive, reproduce, and maintain healthy populations.
It is also critical to note that sound is an essential tool for ensuring national security. The development of underwater sound as a method for detecting submarines began during World War I and accelerated rapidly during World War II. During the Cold War, acoustic antisubmarine warfare became the principal deterrent against missile-carrying submarines roaming the high seas. Since the end of the Cold War ocean acoustics has continued to retain its military significance, but now militaries seek to expose submarine and submerged mine threats in shallow-water areas.
It is in this context of parallel developments and applications in ocean acoustics, marine seismology, oil exploration, and animal bioacoustics that concerns about the effects of sound on marine life have emerged. While researchers had been aware for quite some time of the sounds produced by marine life, it was not until the Acoustic Thermometry of Ocean Climate (ATOC) project (Baggeroer and Munk, 1992), in which high-intensity, low-frequency (defined for this report as sounds below 1,000 Hz) sounds were transmitted over long distances, that the public’s attention focused on the possible impacts of human-generated noise on marine mammals, although noise with potential impacts had been regulated since the passage of the Marine Mammal Protection Act in 1972. Suddenly, it seemed, nearly all sources of anthropogenic sound came under intense scrutiny as potential threats to the existence and well-being of undersea life. These have included not only the aforementioned oceanographic, naval, and seismic surveying tools but also additional sources of unintentionally generated noise, such as commercial shipping, offshore construction, and recreational boating. As a result, research support for marine mammal bioacoustics, principally from the Office of Naval Research (ONR; Gisiner, 1998), grew substantially, and the permitting process necessary for conducting ocean acoustics experiments that allow incidental takes, administered by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Fish and Wildlife Service, received increased scrutiny. Two National Research Council (NRC) panels (NRC, 1994, 2000) were convened especially to address those issues associated with low-frequency sound, with particular attention paid to the ATOC project (NRC, 2000). The current NRC committee, which is responsible for generating this report, was convened at the request of the interagency National Ocean Partnership Program, with support from ONR, the National Science Foundation, NOAA, and the U.S.