The US Navy may soon get the green light to deploy a new, high-tech sonar system in 80 percent of the world’s oceans, despite evidence that it may pose a lethal danger to whales and other marine creatures.
The Low Frequency Active Sonar System is designed to detect a new generation of stealthy submarines by broadcasting sonic signals over thousands of miles of ocean, and then listening for the distinctive echo when the signals bounce off a sub. But some scientists and environmental activists warn that the system can cause hemorrhages in whales’ ears, throats, and brain tissue (see our story Testing the Waters). Government researchers acknowledge that a similar sonar probably injured 15 whales last year in the Bahamas, six of them fatally.
Nonetheless, the National Marine Fisheries Service, a federal agency that enforces laws protecting ocean life, gave a preliminary stamp of approval to a Navy-initiated assessment of the sonar’s environmental impact last month. The study, conducted by independent scientists, concludes that although the sonar produces noises thousands of times louder than the level deemed safe for human or whale ears, the system will only harass, but not harm, whale populations. Navy guidelines for making sure that there are no marine mammals within a kilometer of a sonar broadcast, where the signal is strongest, provide adequate protection, the scientists concluded. Based on those findings, the fisheries service may soon grant the Navy an exemption from a federal law protecting marine mammals.
Critics, however, remain unconvinced. Ken Balcomb, a scientist at the Friday Harbor, Wash.-based Center for Whale Research, has been studying beaked whales in the Bahamas for 10 years. At least, he says, he was studying them, until the entire population disappeared; Balcomb believes the whales were driven away or killed by the Navy’s sonar test.
Balcomb claims that the sonar harms whales via a mechanism different from that studied in the environmental impact statement. While the Navy’s study focused on whales’ hearing, he argues that a “resonance phenomenon” damaged tissue in the whales’ heads in the Bahamas incident. That resonance effect, he says, could be brought about at sonar volumes much lower than what the Navy considers safe, and as a result the Navy’s safeguards for protecting marine life could fail.
Researchers at the National Marine Fisheries Service acknowledge that the sonar could cause dangerous resonance effects that were not studied in the environmental impact report. Dr. Roger Gentry, an acoustics expert with the government agency, says the Fisheries Service is conducting ongoing research in the field of resonance. Researchers at Woods Hole Oceanographic Institute, the largest independent oceanographic research institution in the US, are also looking at the bodies of the whales that died in the Bahamas to see if resonance effects played any role in their demise.
Navy officials insist that the sonar’s strategic importance outweighs its potential ecological costs. “While the environmental rewards (of not deploying the sonar) are unclear, the readiness impacts are real,” Vice Admiral James F. Amerault told a Senate committee in March. Amerault also pointed out that the Navy has sunk some $350 million into the program, and that Russia has already deployed its own low frequency active sonar devices, as has France. Britain, Holland, and NATO are also working on their own types of low frequency active sonar.
Balcomb fears the deployment of these sonars “will cause uncountable whale deaths” — and he means that literally. The sonar’s true toll may never be known, he says, because most dead whales sink to the bottom of the ocean, their deaths unnoticed by humans.