PDF _ RL34403 - Whales and Sonar: Environmental Exemptions for the Navy’s Mid-Frequency Active Sonar Training Program
18-Feb-2009; Kristina Alexander; 18 p.

Update: Previous Editions:
September 27, 2009
April 15, 2008

Abstract: Mid-frequency active (MFA) sonar emits pulses of sound from an underwater transmitter to help determine the size, distance, and speed of objects. The sound waves bounce off objects and reflect back to underwater acoustic receivers as an echo. MFA sonar has been used since World War II, and the Navy indicates it the only reliable way to track submarines, especially more recently designed submarines that operate more quietly, making them more difficult to detect.

Scientists have asserted that sonar may harm certain marine mammals under certain conditions, especially beaked whales. Depending on the exposure, they believe that sonar may damage the ears of the mammals, causing hemorrhaging and/or disorientation. The Navy agrees that the sonar may harm some marine mammals, but says it has taken protective measures so that animals are not harmed.

MFA testing must comply with a variety of environmental laws, unless an exemption is granted by the appropriate authority. Marine mammals are protected under the Marine Mammal Protection Act (MMPA) and some under the Endangered Species Act (ESA). The training program must also comply with the National Environmental Policy Act (NEPA), and in some cases the Coastal Zone Management Act (CZMA). Each of these laws has provisions where a federal action may be exempted from compliance. The Navy has invoked all of the exemptions to continue its sonar training exercises.

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Topics: Natural Resources, Science & Technology

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