Navy expands sonar testing despite troubling signs
SAN DIEGO — The U.S. Navy plans to increase sonar testing over the next five years, even as research it funded reveals worrying signs that the loud underwater noise could disturb whales and dolphins.
Reported mass strandings of certain whale species have increased worldwide since the military started using sonar half a century ago. Scientists think the sounds scare animals into shallow waters where they can become disoriented and wash ashore, but technology capable of close monitoring has emerged only in about the last decade.
Aside from strandings, biologists are concerned marine mammals could suffer prolonged stress from changes in diving, feeding and communication.
Two recent studies off the Southern California coast found certain endangered blue whales and beaked whales stopped feeding and fled from recordings of sounds similar to military sonar.
Beaked whales are highly sensitive to sound and account for the majority of beachings near military exercises. Scientists, however, were surprised by the reaction of blue whales — the world’s largest animal — long thought to be immune to the high-pitched sounds. It’s unclear how the change in behavior would affect the overall population, estimated at between 5,000 and 12,000 animals.
The studies involved only a small group of tagged whales and noise levels were less intense than what’s used by the Navy. Shy species, such as the Cuvier’s beaked whale that can dive 3,000 feet below the surface, have taken years to find and monitor.
“This is a warning flag and deserves more research,” said Stanford University biologist Jeremy Goldbogen, who led the blue whale study published this summer in the journal Proceedings of the Royal Society B.
Navy officials say it’s vital to national security that sailors receive sonar training in real-life conditions.
“If you deafen a marine mammal for even a short period time, you are affecting its ability to survive,” said Michael Jasny of the Natural Resources Defense Council, whose group has sued to force the Navy to add more protections.
The Navy estimates that its activities could inadvertently kill 186 whales and dolphins off the East Coast and 155 off Hawaii and Southern California, mostly from explosives. It calculates more than 11,000 serious injuries off the East Coast and 2,000 off Hawaii and Southern California, along with nearly 2 million minor injuries, such as temporary hearing loss, off each coast. It also predicts marine mammals might change their behavior — such as swimming in a different direction — in 27 million instances.