For years, the United States Navy has been using long-range sonar to scan the world’s oceans for sneaky submarines. The sonar, which can travel hundreds of miles and generate sound waves up to 235 decibels, is known to cause serious harm to marine animals, making communication all but impossible. But now, The Verge reports, the Ninth Circuit Court of Appeals has ruled [PDF] that the regulation allowing the Navy to use its long-range sonar violates the Marine Protection Act. That means the Navy will soon have to drastically reduce its use of marine life-disturbing sonar.

WIRED explains that the National Marine Fisheries Service previously ruled that the Navy could use its long-range sonar so long as they found no evidence of marine mammals in the area. That meant that as long as there was no record of marine animals in a given region of the ocean (a common phenomenon considering vast swaths of the world’s oceans haven’t been surveyed), the Navy was free to use its sonar. The court has now ruled that in the future, the impetus will be on the National Marine Fisheries Service and the Navy to prove that there are, in fact, no marine animals in an area before using sonar.

The ruling marks a great victory for marine animals and environmentalists, who have been trying to reduce the Navy’s use of disruptive sonar for years. In fact, back in 2004, with the help of a human lawyer, the so-called “cetacean community” (all the whales, porpoises, and dolphins in the world) attempted to bring a suit against then-president George W. Bush for permitting the Navy’s use of harmful sonar. (The case was dismissed when the judge ruled animals couldn’t sue humans.) This time, it was several environmental NGOs that took the National Marine Fisheries Service to task, including the Natural Resources Defense Council and the Ocean Futures Society, founded by Jean-Michel Cousteau (son of Jacques Cousteau).

It’s hard to overstate how damaging the impact of long-range sonar can be on marine lives. For animals who rely on echolocation to communicate, it can be a matter of life and death. It can have an impact on eating, navigation, and breeding, and according to Vocativ, may even cause whales to beach themselves.

“It can mean the difference between feeding and not feeding, or breeding and not breeding,” Michael Jasny of the National Resources Defense Council tells WIRED. “It’s important to understand that the ocean is a world of sound, not sight.”

[h/t The Verge]

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