From the March 2005 Idaho Observer:

Navy sonar likely link to mass dolphin suicides

KEY WEST, Florida—Navy and wildlife experts are attempting to determine why about 70 rough-toothed dolphins beached themselves March 2, 2005. Florida Keys National Marine Sanctuary spokeswoman Cheva Heck stated that 20 of the dolphins had died since being found on the beach.

The Chicago Tribune reported that the day before the dolphins beached themselves, the submarine USS Philadelphia had been conducting exercises with a contingent of Navy Seals about 45 miles from Marathon, Florida, where the stranded dolphins were found.

Navy officials reportedly refused to publicly state whether or not the sub was using its sonar during the exercise. The refusal would appear to be a tacit admission that the navy was using sonar during the exercise.

Standard procedure for U.S. ships when not "running silent" is to project low-level sonar soundwaves to locate obstacles in their immediate path. But sharper bursts of sonar for mineral exploration and other purposes can be heard by marine mammals for miles away from the source and can penetrate the ocean floor at depths up to 150 feet.

Some scientists believe that loud bursts of sonar may disorient or scare marine mammals, causing them to surface too quickly and suffer the equivalent of what divers know as the bends, nitrogen bubbles in tissue caused by sudden decompression.

Similar beaching events have been occurring in locations all over the world for the last two decades. Most recently off the coast of Australia, hundreds of whales and dolphins have been beaching themselves (over 3,000 in the last nine years). The cause of so many marine mammals committing mass suicide continues to be identified as a "mystery."

Coincidentally, the Australian government has been giving tax incentives to corporations willing to conduct mineral exploration operations off the nation’s coast (The Idaho Observer, January 2005).