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  #11  
Old 05-14-2010, 01:35 PM
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I just thought about water sonar devices that could explain the deaths
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  #12  
Old 05-14-2010, 03:26 PM
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I just thought about water sonar devices that could explain the deaths
Well we did have a few whale deaths years ago (approx 2004-2005) that corresponding with the testing of a sonar system by the USS Shoup near the Strait of Juan de Fuca. Similar events have been reported to have corresponded to some oceanographic research projects as sonar also has applications there, especially with geological research. However, almost every incident that I have heard of resulted in a stranding of whales rather than the washing up of a dead whale. While sonar related incidents sometimes involve individual animals a lot of them involve groups of just under a dozen to as much as a hundred or more individuals across several species.

I was a naval midshipman when the Shoup incident took place and met a rear admiral who used to work in a department in the navy that dealt with environmental concerns. He had no doubt that when a ship went active with its sonar that any critter nearby was going to get its bell rung as he put it. Whether or not it would be harmed, he had his doubts. Strictly speaking, while there has been very strong suspicion for a number of decades that sonar could be harmful, as far as I know the mechanism behind it is not understood, though I'm familiar with at least one hypothesis. Generally the navy doesn't like to ping away with active sonar to begin with because doing so pretty much announces your presence and location anyone that can hear it. This is especially true with submarines and passive sonar is usually preferred. Surface ships tend to be more liberal with the use of active sonar because they aren't as stealthy as submarines to begin with and under wartime conditions they can safely assume that a submarine in the area is already aware of their presence.

The concerns regarding naval sonar seems to correspond with a shift in the kind of sonar used. WWII sonar operated at higher frequencies which was short range. In the decades that followed navies began to shift to lower frequencies to take advantage of SOFAR channel (Sound Fixing and Ranging channel) which is a horizontal layer of water in the ocean in which the speed of sound is at a minimum. It acts as a waveguide for sound in the ocean and can carry sound for thousands of miles. This layer was first described in the 1940s by Dr. Maurice Ewing and Leonid Brekhovskikh. However the idea that whales used this layer as well didn't come around till the 1970s. It's been proposed that before the days of propellers, whale sounds could travel 13,000 miles before the intensity decreased to the level of background noise. I'm not familiar with the specifics of the physics behind the SOFAR channel, but some some of the example water column profiles I've seen regarding the subject seem to suggest temperature and pressure are factors.
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Old 05-14-2010, 05:11 PM
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The vestibular system might be completely going crazy... and it has been discovered that the whales rise too fast and get gas embolism with decompression sickness.
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Old 05-14-2010, 05:48 PM
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The vestibular system might be completely going crazy... and it has been discovered that the whales rise too fast and get gas embolism with decompression sickness.
Yeah, that's pretty much what I'm familiar with. I don't know if it's ever been observed that whales have risen too fast after exposure to sonar pings, but necropsies of whales from past events have shown gas embolisms in their tissues which suggests that they've risen too fast. I don't have the same access to papers like when I was in college. I wouldn't at all be surprised if their vestibular goes out of whack after being subjected to such noises. They rely on sound just as much as we rely on light in our daily lives. For them being subjected to such high intensity sounds would probably be like one of us being near a flash bang grenade.

For us a flash bang is pretty harmless, but we don't live in an environment where we move from one extreme set of conditions to another. Whales deal with extreme pressure changes among other things and pressure affects a lot of things in biology chemistry and physics. It's just like if you've been following the spill in the Gulf of Mexico. The "ice" that is constantly being mentioned in the news is actually a substance called methane clathrate hydrate, sometimes called fire ice because it does burn. At one atmosphere of pressure it behaves like ice in that it will melt just above zero degrees C. At high pressures though, it can remain stable at temperatures as high as 18 degrees C which is just shy of room temperature.
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Old 05-15-2010, 02:31 AM
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I'd really like to study such cases, but I'm too far away from a coast
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