HONOLULU — The U.S. Navy says its training and testing using sonar and explosives could potentially hurt more dolphins and whales in Hawaii and California waters than previously thought.
The new research and more thorough analysis are part of a draft environmental impact statement covering Navy training and testing planned for 2014-2018. A notice about the study is due to appear in the Federal Register on Friday.
In the study, the Navy estimates its use of explosives and sonar may unintentionally cause more than 1,600 instances of hearing loss or other injury to marine mammals in one year. The service calculates that its use of explosives may inadvertently cause more than 200 marine mammal deaths a year.
The old Navy analysis — covering 2009-2013 — estimated the service might unintentionally cause injury or death to about 100 marine mammals in Hawaii and California, although no deaths have been reported.
The Navy isn't saying it will injure whales and dolphins as it trains sailors and tests equipment. It's telling the public and environmental regulators that its actions have the potential to harm or otherwise prompt a reaction in the animals.
The Navy takes a variety of measures to prevent harm to the animals, including turning off sonar when marine mammals are spotted nearby. It says the actual numbers of injured animals would be lower as a result.
The Navy must provide the information to the National Marine Fisheries Service to earn a permit for its activities. If it didn't do so and was later found to have harmed marine mammals, it would be found in violation of federal environmental law and have to stop its training and testing.
Some reasons the Navy is predicting a greater impact is its use of new research on marine mammal behavior and updated computer models that predict how sonar affects animals.
The Navy also expanded the scope of its study to include things like in-port sonar testing — something sailors have long done but wasn't analyzed in the Navy's last environmental impact statement. The analysis covers training and testing in waters between Hawaii and California for the first time as well.
"Each time around, each time we swing through this process, we get better, we take a harder look, we become more inclusive," said John Van Name, senior environmental planner at the U.S. Pacific Fleet.
Zak Smith, staff attorney at the Natural Resources Defense Council, said he's encouraged the Navy reduced the threshold for the level of sonar it found to affect beaked whales — a species that appears to be particularly sensitive to the noise.
The Navy said it changed the threshold because research has shown beaked whales move away and otherwise react when exposed to a lower level of sound than earlier studies indicated.
"My first glance shows there's positive steps," Smith said after he took a quick look at the 1,800-page document. But he said he would have to look at the details before giving his full assessment.
The Navy uses sonar to track enemy submarines, torpedoes, mines and other potential threats underwater. Sonar operators send pulses of sound through the ocean and then listen for echoes from objects hit by the sound waves.
Scientists say the sound may disrupt the feeding patterns of marine mammals. The sound may also startle some species of whales, causing them to surface rapidly.