The Use of Psychoacoustics in Marine Mammal Conservation in the United States: From Science to Management and Policy

Abstract

Underwater sound generated from human activities has been long recognized to cause adverse effects on marine mammals, ranging from auditory masking to behavioral disturbance to hearing impairment. In certain instances, underwater sound has led to physical injuries and mortalities. Research efforts to assess these impacts began approximately four decades ago with behavioral observations of large whales exposed to seismic surveys and rapidly progressed into the diverse field that today includes studies of behavioral, auditory, and physiological responses of marine mammals exposed to anthropogenic sound. Findings from those studies have informed the manner in which impact assessments have been and currently are conducted by regulatory agencies in the United States. They also have led to additional questions and identified information needed to understand more holistically the impacts of underwater sound, such as population- and species-level effects, long-term, chronic, and cumulative effects, and effects on taxa for which little or no information is known. Despite progress, the regulatory community has been slow to incorporate the best available science in marine mammal management and policy and often has relied on outdated and overly simplified methods in its impact assessments. To implement conservation measures effectively, regulatory agencies must be willing to adapt their regulatory scheme to ensure that the best available scientific information is incorporated accordingly.

Moderate Anthropogenic Noise Exposure Does Not Affect Navy Bottlenose Dolphin (Tursiops truncatus) Whistle Rates

“…Concerns about exposure to anthropogenic noise from commercial shipping, military sonar, oil and gas exploration, and off-shore construction has motivated significant research into the effects of noise on marine mammals. Behavioral changes in the presence of anthropogenic noise have been observed in many species of marine mammal, although the received levels (RLs) at which the change was observed varied depending on the sensitivity of the species [28,29,[32][33][34][35][36][37]. For example, northern bottlenose whales (Hyperoodon ampullatus) exhibited an avoidance response from RLs between 117 and 126 dB re 1 µPa [37], North Atlantic right whales (Eubalaena glacialis) stopped feeding when exposed to RLs between 133 and 148 dB re 1 µPa [38], and long-finned pilot whales (Globicephala melas) had a higher probability of behavioral response to tactical sonars greater than 165 dB re 1 µPa [39].…”