Roger Gentry, an expert on marine mammal acoustics at the U.S. National Oceanic and Atmospheric Administration in Silver Spring, Maryland, said researchers were unable to confirm whether the damage was sustained when the beaked whales came ashore, or whether it was caused by the sonar itself. But scientists did confirm that the strandings were likely to be linked to the sonar, Gentry said.
Gentry and others have provided the U.S. Navy with a map of beaked whale global hot spots to help mitigate further beaching incidents.
"The problem is that we are seeing military sonar exercises in habitats not used before," Gentry said. "Previously, antisubmarine sonar exercises were carried out deep offshore. But warfare has changed."
The development of ultraquiet, diesel-electric submarines (which have the potential to travel undetected and fire missiles inland) has meant that military drills are required close to shore, Gentry said.
Gentry also notes the need to monitor marine canyonswhich are not only perfect spots for subs to hide in, but also favored habitats of various species of beaked whales.
Gentry concurs that, while most evidence links the negative effects of new sonar to beaked and possibly minke whales, it is plausible that killer whales are also adversely affected by sonar.
Balcomb, the orca expert, filmed the May 5 incident. His footage provides the very first hints that killer whales might react to sonar, commented Robert Gisiner. Gisiner is a marine mammal expert at the Office of Naval Research in Arlington, Virginia.
Gisiner notes that there is a pretty clear correlation between beaked whale strandings and the use of mid-frequency sonar off Madeira (also located off northwestern Africa) and the Canary Islands. "However, we don't really know how the effects on beaked whales occur," he said. "It's hard to say at this stage whether the same thing is happening to killer whales."
Autopsies of porpoises stranded near Puget Sound last May proved inconclusive. But Balcomb said he is fighting, nonetheless, to prove that sonar is dangerous to orcas too.
Next month Balcomb and a group of scientists, naval representatives, and government officials will present evidence on the threat from sonar to the United States Marine Mammal Commission, the Washington, D.C.-based federal commission that provides the President with guidance on the Marine Mammal Protection Act. The hearing is to be the first of three to be held this year.
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