Proving a Negative
This article in the Virginia Pilot on the proposed Navy Sonar Range and accompanying discussion of the possible effects of active sonar use on marine mammals shows what the Navy is up against whenever there's a beaching of whales or dolphins. Excerpt:
"The Navy concedes that its use of mid frequency sonar contributed to the stranding of 17 whales and dolphins, seven of which died, during sonar training in the Bahamas in 2000 , an event it had initially characterized as an unfortunate coincidence unrelated to its exercises.
"There are other possible links between mid frequency sonar and animal distress :
"Hours after NATO naval exercises off the Canary Islands in 2002, 14 beaked whales stranded and died. Scientists later determined that 10 of the animals had developed nitrogen gas bubbles in their tissues and blood vessels, possibly from surfacing too quickly in reaction to sonar.
"In waters off Washington state in 2003 , a Pacific-based destroyer was conducting sonar exercises at the same time a pod of killer whales was observed behaving erratically. Within a month of that drill, 14 harbor porpoises were found dead. A government report concluded that it was impossible to tell whether the whales had suffered hearing loss or whether the dead animals showed signs of acoustic trauma.
"As many as 200 melon-headed whales in Hanalei Bay, Hawaii, came unusually close to shore and showed clear signs of stress in 2004 . A six-ship group of U.S. and Japanese naval vessels had started sonar exercises 20 miles away that morning."
As you can see, anytime there are sonar exercises anywhere in the vicinity of a beaching, people will immediately blame the active sonar. While sonar use probably does contribute to some of the beachings, it's also clear that there are many other beachings which aren't related to sonar use; conversely, there are many times the sonar is used in the vicinity of marine mammals that don't lead to adverse effects. I think the most important thing for everyone involved is to set up some reasonable rules for the operation of the new range while still recognizing that it serves a vital military purpose.