The blue whale is one of the largest animals ever known to have lived on Earth, but despite its heft, this magnificently oversized marine mammal can’t withstand the biological blows caused by Navy sonar training and testing.

Today, the blue whale got a break from these harmful sounds. For the first time ever, the U.S. Navy has agreed to put vast swaths of important habitat for numerous marine mammals off limits to dangerous mid-frequency sonar training and testing and the use of powerful explosives.

Areas around the Maui 4-Island Complex, where certain U.S. Navy activities will be limited under the settlement. 

The significance of this victory cannot be overstated. Ocean noise is one of the biggest threats to the health and well-being of marine mammals, which rely on sound to “see” their world. For years, scientists have documented that high-intensity, mid-frequency sounds wreak havoc on the aquatic environment, causing serious impacts to marine mammals, such as strandings, habitat avoidance and abandonment, and even death.

In fact, the Navy’s own five-year Pacific weapons testing and training plan said as much, estimating that whales, dolphins and other marine mammals would be harmed nearly 9.6 million times during high-intensity sonar exercises and underwater detonations. These harmful impacts include millions of instances of temporary hearing loss and significant disruptions in vital behaviors, such as rearing young, as well as more than 150 deaths.

For years the Navy has ignored these impacts, refusing to set aside biologically important areas to minimize harm to these vulnerable marine populations. In 2013, Earthjustice sued the National Marine Fisheries Service for approving the Navy’s five-year plan, alleging violations of the National Environmental Policy Act, the Marine Mammal Protection Act and the Endangered Species Act.

Two years later, in March 2015, a federal judge agreed with us and found that the Navy and the fisheries service violated the law. Today, after months of negotiations among all parties, the Navy has agreed to create safe havens to protect these vital marine species.

“If a whale or dolphin can’t hear, it can’t survive,“ said David Henkin, the Earthjustice attorney who brought the initial challenge to the Navy’s latest round of training and testing on behalf of several groups. “By agreeing to this settlement, the Navy acknowledges that it doesn’t need to train in every square inch of the ocean and that it can take reasonable steps to reduce the deadly toll of its activities.”

Until it expires in late 2018, the agreement will protect habitat for the most vulnerable marine mammal populations, including endangered blue whales, for which waters off the coast of Southern California are a globally important feeding area. It will also protect numerous small, resident whale and dolphin populations off Hawai‘i, for whom the islands are literally their only home.

Today’s announcement proves that the Navy can both protect U.S. naval waters and protect whales and dolphins by limiting the use of sonar and explosives in vital habitats.