Ocean Noise in the News
Whales found at risk
Navy sonar might kill, NOAA says
February 18, 2006
The federal agency charged with protecting marine mammals says the Navy should consider that a proposed sonar range off the North Carolina coast could kill whales.
The National Oceanic and Atmospheric Administration questions the Navy's fundamental assumptions about risks from the sonar range. The most dramatic difference concerns whether sonar could cause whales to beach -- a fatal prospect the Navy has dismissed.
The NOAA raised its "significant concerns" in official comments on the proposed 661-square-mile range to train sailors and pilots to track submarines using pulses of sound bounced off submerged objects to "see" underwater.
The Navy had no comment Friday on NOAA's position but will be obliged to address its concerns because it needs the agency's authorization under federal environmental law for activities that might harm or kill marine mammals. The Navy will respond in writing this fall to all comments submitted on its study, a spokesman said.
North Carolina is the Navy's preferred site among three choices; the others are off Virginia and Florida. A range would be built over 10 years at an estimated cost of $98 million.
The Navy draft study said sonar exercises would disturb some whales, but it rejected the possibility of deaths. Environmentalists and, now, NOAA disagree.
"These Navy sonar systems are very powerful and have the potential to kill marine mammals -- at least in some situations," said Steve Leathery, chief of protected resources permitting for National Marine Fisheries Service, part of NOAA. "It wasn't historically perceived as being as big a problem as we now recognize it is."
Scientists have linked several fatal whale beachings to the use of midfrequency sonar, although they don't understand exactly how the underwater pulses of sound harm the animals. NOAA says the Navy must take such evidence seriously.
"We're not suggesting that there are going to be mortalities," Leathery said. "We are suggesting the potential exists, especially for beaked whales."
Beaked whales, about which little is known, live in deep water and have shown sensitivity to sonar.
NOAA also questions the Navy's conclusion that highly endangered North Atlantic right whales will not be bothered by a range. Only about 320 of the enormous creatures survive; biologists say their future is uncertain. "We consider the death of a single right whale to be further imperiling the species," Leathery said.
In its environmental study, the Navy said the animals hug North Carolina's shore while migrating south to calving grounds and north to summer territories. That means they would not be bothered by sounds generated 47 miles offshore, the Navy has said.
But scientists and environmentalists have unearthed evidence that right whales venture closer to the favored range site than the Navy has acknowledged. Also, last winter, a right whale mother and calf were observed off Johnnie Mercer's Fishing Pier in Wrightsville Beach. That suggests waters off North Carolina may play a more important role than merely serving as a route to and from calving grounds.
"NOAA is absolutely correct to say that the Navy should be thinking more about the North Atlantic right whale, not just at the proposed range. Obviously there will be enhanced traffic to and from there," said UNC-Wilmington marine biologist Ann Pabst.
NOAA also questions the Navy's conclusions about the volume at which noise poses risks to whales and dolphins. The Navy concluded that 190 underwater decibels or higher could disturb the animals, based on studies conducted on four captive dolphins and two captive white whales.
But NOAA, in its comments, says scientists can't assume that captive animals will respond to noise as those in the wild do. Studies conducted on whales in the wild by scientists and the National Marine Fisheries Service suggest that whales respond to sounds quieter than 190 decibels.
Sometimes animals leave an area when they encounter even faint noise, meaning they could be chased from an area important for feeding or another purpose. Or they quit foraging, or swim rapidly to the surface, which could disrupt their normal activities or, worse, put them in a ship's path.
Challenging the Navy
Michael Jasny, a lawyer and consultant for the Natural Resources Defense Council, which is suing the Navy over its use of sonar, said the NOAA comments show the Navy's assumptions are unsupportable.
"It's clear the Navy didn't even consider environmental factors until after they chose North Carolina," Jasny said. "Because of the potential environmental impacts of concentrating so much sonar activity in this area, and because it would become a model, it is essential that they get it right the first time."
The Navy has acknowledged that its midfrequency sonar caused a fatal whale stranding when 17 beaked whales beached in the Bahamas after exercises in 2000.
But scientists suspect Navy mid-frequency sonar has caused other strandings, including incidents in the Canary Islands in 2002 and in Hawaii in 2004. It's still not clear what role sonar played in an unusual stranding of more than 35 whales off North Carolina's Outer Banks in January 2005. A preliminary National Marine Fisheries Service report on the incident called sonar a possible culprit but a later report said it was one of a number of possible causes.