For years, environmentalists have been speaking up about the dangerous effects of military sonar testing on whales. Since such testing began in the 1950s, the number of mass strandings of whales and dolphins has risen significantly, occurring every year in places including the Canary Islands, the Bahamas and Greece.
Two new studies closely link noise pollution produced from testing conducted by the British and U.S. military to mass strandings of whales and dolphins. Post-mortem examination of beach whales has shown that they were bleeding from their ears and suffered from decompression sickness — known as “the bends” to scuba divers — from swimming too quickly to the ocean’s surface. The resulting change in pressure generates lethal nitrogen gas bubbles that clog an animal’s blood vessels.
Beaked whales are the species most known to be disturbed by the sonars, perhaps because they are smaller, shyer in nature and more likely to misinterpret the noise as that of killer whales. Scientists have learned that beaked whales have a strong response to sonars at noise levels far below those the U.S. Navy uses for testing. They have also discovered that blue whales, the largest animals on the planet, also show what seems to be distress from sonars.
To measure the amount of noise whales are subjected to and their response, scientists in the first study attached digital devices to Cuvier’s beaked whales off the coast of Southern California. According to the Guardian, they learned that:
When a simulated military sonar signal was sounded at 200dB and between 3km and 10km away, the whales initially stopped feeding and swimming. They then swam rapidly away from the noise and some performed unusually deep and long dives.
The whales also did something unusual — they stopped feeding for 6-7 hours. Stacy DeRuiter, at the University of St. Andrews in Scotland, notes that populations of Cuvier’s beaked whales are indeed declining and emphasizes that sonars are contributing to the whales going hungry.
In the second study, scientists found that blue whales off the coast of Southern California can be so “spooked” by sonars that their feeding is also affected.
Jeremy Goldbogen of Cascadia Research explains that, ”Blue whales rely on large aggregations of dense krill to sustain their extreme body size, so they continuously dive and feed throughout the day when high-density prey patches are present.” When driven away from their feeding grounds by the sonars, blue whales can end up going without a whole day’s worth of food, a ton of krill.
The U.S.Navy, which partially funded the studies, notes that it reviews its use of sonars annually and would take the new research into account. It says the whales are simply exhibiting a behavioral response by swimming away.
Conservationists, such as Sarah Dolman of the Whale and Dolphin Conservation, argue otherwise: “For whales and dolphins, listening is as important as seeing is for humans – they communicate, locate food, and navigate using sound.”
Noise pollution is indeed a very significant threat to whales and dolphins as it forces them away from feeding and breeding sites and can even cause injury or death. Whales, dolphins and other marine wildlife are now subjected to increasing amounts of noise pollution not only from military sonars but from oil and gas companies using machinery to locate buried oil and gas deposits via a technique called reflection seismology that emits loud pulses of sound. Climatologists also use low-frequency sonars to study changes in ocean temperature. Even more, the huge increase in commercial shipping traffic has resulted in what Nature.com says is an “almost 16-fold increase in background noise intensity in places like the waters off the coast of California.”
Since 2010, the NOAA has said that it is working on creating a comprehensive “noise budget” for the oceans by assessing how much noise pollution is caused by human technology. The need for such regulations is imperative; as Dolman says, there are currently “no accepted international standards regarding noise pollution.”
The deaths of so many whales and dolphins are more than enough reason for us to create such standards and enforce them. Just because we do not hear the horrible racket we create underwater does not mean it does not exist and that untold numbers of animals are in danger of starving and dying.
Photo via Wikimedia Commons