Whales and Sonar: Environmental Exemptions for the Navy's Mid-Frequency Active Sonar Training

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 is 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.

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Document Details

Document Type
Technical Report
Publication Date
Nov 14, 2008
Accession Number
ADA491231

Entities

People

  • Kristina Alexander

Organizations

  • Library of Congress

Tags

Communities of Interest

  • Ground and Sea Platforms
  • Human Systems
  • Sensors

DTIC Thesaurus Topics

  • Acoustic Propagation
  • Active Sonar
  • Ear
  • Endangered Species
  • Environment
  • Fish
  • Frequency
  • Habitats
  • Law
  • Marine Mammals
  • Medical Personnel
  • National Security
  • Odontocetes
  • Sonar
  • Training
  • United States
  • Wildlife

Readers

  • Acoustical Oceanography.
  • Marine Mammal Biology