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How the Navy’s Sonar Technology Has Been Harming Whales

The loud pulses of sound can disrupt the mammal’s hearing, communication, and mating habits.

By Madeleine Thomas


(Photo: Wikimedia Commons)

A type of high-intensity sonar used by the United States Navy across more than 70 percent of the world’s oceans is illegal, the Ninth Circuit Court of Appeals in California ruled last week.

Low-frequency active sonar — believed to be one of the best methods for detecting foreign submarines — has been employed by the Navy all over the world, including the Pacific, Atlantic, and Indian Oceans, and the Mediterranean Sea. But the loud pulses of sound also put baleen whales, sperm whales, seals, and walruses in harm’s way as they travel thousands of miles underwater, according to the court ruling.

Sonar exposure muddles nearly all of the mammals’ natural behaviors. It can disrupt their hearing, communication, and mating habits; lead them to stop foraging for food; and provoke them to separate from their calves. As Pacific Standard has reported before, some experts want the U.S. to follow the European Union’s lead and recognize marine noise as a pollutant.

The National Marine Fisheries Service has strict requirements for using sonar — including how close the Navy can employ sonar transmission near coastlines and other biologically important marine areas. But Friday’s court ruling deemed that even though the NMFS permitted the Navy to start using low-frequency act sonar in 2012, the practice violates requirements established in the Marine Mammal Protection Act.

“We have every reason to believe that the Navy has been deliberate and thoughtful in its plans to follow NMFS guidelines and limit unnecessary harassment and harm to marine mammals,” the ruling states. “This systematic underprotection of marine mammals cannot be consistent with the requirement that mitigation measures result in the ‘least practicable adverse impact’ on marine mammals.”