SAN FRANCISCO — The federal agency tasked with granting the U.S. Navy permission to use low-frequency active sonar for training, testing and routine operations in oceans around the world didn’t do enough to protect marine mammals, a panel of judges in the Ninth U.S. Circuit Court of Appeals decided recently.

Advocates, including the Natural Resources Defense Council and the Humane Society of the United States, sued the National Marine Fisheries Service over a permit it approved in 2012, allowing the Navy to use sonar that can travel long distances and detect quiet submarines. It also has the potential to harm or disorient marine mammals who are too close.

The lawsuit claimed the Fisheries Service wasn’t following its mandate to limit activity that could harm marine mammals. Under federal law, the agency is supposed to promote the least adverse impact on marine mammals, but it settled for a lesser standard.

The three-judge panel determined the agency “did not give adequate protection to areas of the world’s oceans flagged by its own experts as biologically important,” according to court documents.

The NRDC is happy with the panel’s unanimous decision, which was filed July 15, Zak Smith, an attorney in the council’s land and wildlife program, told the Northern California Record.

“It was a well-reasoned, strong opinion that really got at the heart of the issue,” Smith said. “It was a responsibility that (the Fisheries Service has) been shirking. These statutes are very clear on their face — they’re supposed to maximize benefits for marine mammals.”

He said rather than identifying ways the U.S. Navy could do more to protect marine mammals from sonar noise, the Fisheries Service was too easily satisfied with the protections the Navy suggested.

“That’s the real problem. The Fisheries Service never really took up the mantle that their job is to maximize protection. This ruling from the court makes it clear that no, that is their job. We were very happy with it,” Smith said.

From here, the case could be appealed to the entire Ninth Circuit or to the U.S. Supreme Court. Smith said he doesn’t know what action either side of the lawsuit will take.

This is the third time the NRDC has sued the permitting agency over this issue. Previous cases were settled while in district court. Smith said he expects the agency will obey the law after the Ninth Circuit’s ruling.

“I think from this decision, which is very strong and very clear, the Fisheries Service will have to approach its consideration of protective measures in a very different way than it has in the past,” he said.

Whales, dolphins, walruses and other marine mammals rely on underwater sound for things like catching prey, communicating and navigating. Low frequency active sonar can have a range of effects on these marine mammals. The sonar can alter their behavior: If a mammal is feeding, mating or taking care of its young, it may stop and abandon the area. This could be out of fear — such as if the sound resembles a predator — or it could be because the noise is so disorienting or disruptive. But the noise could also hurt a mammal that is close enough to the source of the sound.

“You’re putting a very intense sound into the ocean environment,” he said. “If you’re close to a loudspeaker, you could suffer physical injury from that. … And it isn’t just like a loudspeaker, it’s really the blast radius, so to speak. The pressure of the sound moving through the water is so intense that it can actually cause physical harm.”