NOAA’s sound mapping project aims to help protect marine mammals.
Image: Captain Budd Christman, NOAA

The Navy’s use of sonar in Hawaiian waters is getting increased scrutiny as a federal agency documents and maps human-caused noise pollution in the oceans in an attempt to dim the din for the sake of marine mammals.

Cetaceans–dolphins, whales and porpoises–are very sensitive to underwater noise. Their hearing is acute, and they rely upon sound signals to communicate and find food. As the National Oceanic and Atmospheric Administration (NOAA) determines where noise from ship traffic, military sonar and offshore oil drilling is most heavily concentrated, it is also mapping areas important to cetaceans for feeding, breeding and migrating. This will reveal whether noise is intruding into their habitat.

The project is focusing initially on commercial ship traffic, because it’s ubiquitous and ongoing. But it will also look at the Navy’s use of sonar, says Michael Jasny, director of the Natural Resources Defense Council’s marine mammal project, which has sued the Navy over its use of sonar in training exercises off Hawaii and California.

“When the Obama Administration took office, NOAA did some soul-searching and concluded in a memo to the White House that the mitigation it had approved for the Navy’s sonar was inadequate,” Jasny explains. “NOAA committed itself to undertaking a number of steps to improve things, the most important of which is this mapping.”

The revised mitigation measures likely won’t surface until early 2014, when the National Marine Fisheries Service is expected to issue five-year rules for offshore sonar and explosive ordinance training.

In the meantime, the mapping is “enormously useful for management of cetaceans,” Jasny says. “It’s no surprise that waters immediately around the Hawaiian Islands are clearly important for a large number of species.”

A number of species that are typically far-ranging, such as false killer whales, have established distinct resident populations around the Islands. “[T]hese small populations can be quite vulnerable to harm from man-made noise,” Jasny says, stressing that, “The science has been clear on the vulnerability of Hawaiian populations and the need to put certain habitats off limits.” In addition, the project will “light a fire under the International Maritime Organization” to develop guidelines for reducing noise from ships, Jasny says.