SAN DIEGO — The 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 that 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 is 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 is used by the Navy.