Whale Deaths Linked to Undersea Blasts

Intense underwater noise or explosions caused a mass stranding of healthy beaked whales in the Bahamas in March while the U.S. Navy was conducting tests in the area, federal marine specialists said Wednesday.

The report to the National Oceanic and Atmospheric Administration does not explicitly conclude that Navy sonar tests or explosions caused the deaths, but it does say the hemorrhages found in or around the animals’ ears are consistent with the effects of a “distant explosion, or an intense acoustic event.”

The findings are the first to link either distant noise or a faraway explosion with a whale stranding, said Darlene Ketten, an auditory specialist at the Woods Hole Oceanographic Institution who helped conduct necropsies on six of the whales for NOAA. She called the conclusions “a red flag” and “a reason for concern.”

In a letter to NOAA also released Wednesday, Assistant Secretary of the Navy Robert B. Pirie Jr. wrote that the Navy recognized that the Bahamas stranding was “an unusual and significant event” and that the service was cooperating in the ongoing investigation of the whale deaths.

If naval sonar testing can cause trauma in whales, he wrote, the Navy will reassess its use of sonar tests during peacetime training and act to try to minimize the adverse impact on the whales.

The Navy has been experimenting with a variety of high-intensity and low-frequency sonar systems that emit loud noise blasts underwater, spending $350 million over the last decade. The systems are needed, the Navy says, to track the growing number of quiet, diesel-electric submarines operated near sensitive coastlines by unfriendly nations.

The report was immediately embraced by opponents of Navy acoustic testing as a “smoking gun” that shows new and high-power sonar systems can disorient and kill whales and other sea mammals.

“You are never going to see any clearer evidence that active acoustics like those used by the Navy can cause whales to die,” said Andrew Wetzler, an attorney with the Natural Resources Defense Council. The council and other environmental groups have been challenging Navy underwater systems since the mid-1990s.

“The Navy is trying to present this as something particular to beaked whales, but we think these systems are a danger to all whales,” he said.

Sixteen whales and dolphins became stranded on two beaches in the Bahamas in March, and seven of the animals ultimately died. Six of the dead animals were beaked whales, a relatively small (16 to 20 feet) and reclusive species known to dive deeper than most other whales.

Few whale strandings have ever been explained, and most are never discovered. But the Bahamas stranding was reported quickly, and six of the seven dead animals were in good or excellent shape for necropsy, the animal equivalent of an autopsy.

According to Ketten, the whales were in otherwise good health--showing no signs of disease, malnutrition or poisoning--when they became disoriented and stranded themselves.

All six beaked whales had some evidence of tissue trauma associated with hearing, sound production, and air intake, the NOAA report said. The animals that died would have experienced the equivalent of a “really bad headache”--one that would send a human to the hospital, Ketten said.

Many scientists believe that whales and other marine mammals can be harmed by the extremely high-decibel sounds created as part of the Navy’s “active” sonar systems, but Ketten said Wednesday there wasn’t enough evidence yet to make that direct connection in the Bahamas strandings.