Is the use of sonar by man harmful to ocean animals?
The potential impacts of sonar on marine animals are similar to those of humans exposed to noise and include: • behavioural changes; • temporary or permanent hearing loss or tissue damage; and • physiological stress responses. The species affected by the sound depends on the frequency and sound pressure level. For example sound sources such as airguns produce more noise in the hearing range of baleen whales than mid-frequency echo sounders, which produce more noise in the ranges used by seals and toothed whales. Sounds that disturb one species appear to have no effect on others. The potential risks to animals posed by the use of sound by humans result from a combination of the energy level, frequency and local acoustical effects due to the underwater landforms. Instruments of sufficiently low power and high frequency pose a minor risk. The equipment with the highest risks are airgun arrays and low frequency, high-power transducers with wide beam angles. How can we tell if an animal is
