The U.S. Minerals Management Service (MMS) manages the oil and gas resources of the Outer Continental Shelf (OCS) in a manner that seeks "to ensure that all activities on the OCS are conducted with appropriate environmental protection and impact mitigation" (USDOI, MMS 2002). To this end, MMS sponsors studies to evaluate environmental impacts of OCS activities and to identify appropriate mitigation measures. Since the 1970s, one focus has been on the potential for impact of anthropogenic noise on marine mammals. Marine mammals are adapted to use sound in the ocean for communication, navigation, localizing and using prey, and sensing of the environment. These animals have evolved in an ocean that is filled with natural sounds. Humans began to introduce significant additional sound sources with the advent of the industrial age in the mid-nineteenth century. As the power and number of these sound sources increased, the potential for impacting marine mammals increased as well. Of concern are the potentials for negative behavioral and physiological responses to human-generated sound, at both the individual and population levels.