Harmful effects of sonar

Recently I came across an article talking about the effect that the U.S. navy’s sonar signals have on marine life. The only visible impact that sonar has made so far is the unusually high amount of stranded whales in Hawaii, the U.S. Virgin Islands, Greece and other places around the world. Now I know this may sound like another “save the whale” kind of a story, but I never thought about sonar activity and its impact on marine life and I’m guessing I’m not the only one, so I thought it would be interesting to talk about.

Apparently the U.S. Navy openly admits that their training with sonar does in fact have harmful effects on marine life and even estimated that within the two years they planned on training, they would be disturbing 17,000 marine mammals, permanently injure more than 500 whales and cause temporary hearing impairment in at least 8,000 others. I do want to say that I’m not trying to knock down the US Navy. I think training exercises are important for any kind of servicemen. But, like it said in the article, we should not have to choose between the US Navy and natural resources, such as wildlife.

Wildlife has already taken a hit over the centuries because of man’s impact. Most of the wildlife tragedies we have seen have been on land, who knows how many extinctions or major habitat changes we impacted in deep waters. The NRDC filed a case against the U.S. Navy in 2008 and within that case file was a list of suggestions that the U.S. Navy could put into action to lessen its sonar impact on marine life. Some of them included “Refrain from using sonar within 12 nautical miles of the CA coast and in certain vulnerable whale habitats” and “stop using sonar when marine mammals are spotted within 2,200 yards of a sonar-emitting vessel”. I’m not very familiar with US Navy or its training requirements so I can’t really comment on how fair I think their suggestions are but I do think that the US Navy could implement the following suggestion made by the NRDC: “Power down sonar by 6 decibels during “surface ducting” conditions.” Surface ducts are areas in the water where the sound waves are channeled better, making the noise more intense for the whales. Even if a whale is 300 miles away from the sonar source, if the waves emit an intensity of 140 decibels, it is a hundred times more intense than that known to alter the behavior in whales. Some of the navy’s operating systems emit more than 235 decibels of sound waves causing what divers know as “the bends” when they surface too quickly and cause bleeding around the brain, ears and large bubbles in their organs.

I realize that the US Navy cannot totally avoid this problem. Training is necessary and I don’t mean to downplay that. However I would like to do more research to see if they are at least trying to make certain adjustments to lessen their impact while we can still stop it before its too late.
Sources: Natural Resources Defense Council