Comments on: EarthTalk: Sonar? Microwaves? http://blastmagazine.com/the-magazine/culturefashion/2009/05/earthtalk-sonar-microwaves/ Music, movies, tv, video games, tech, food, drink, young, hip, and sexy! Sun, 22 Nov 2009 06:11:01 -0500 http://wordpress.org/?v=2.8.6 hourly 1 By: Jim Cummings http://blastmagazine.com/the-magazine/culturefashion/2009/05/earthtalk-sonar-microwaves/comment-page-1/#comment-10036 Jim Cummings Thu, 28 May 2009 16:50:23 +0000 http://blastmagazine.com/?p=15101#comment-10036 Good try at answering a difficult question. I'm afraid you're off on some of the technical facts, though. In California, Navy estimates were that their training mission would result in 170,000 "takes" of marine mammals; this is not deaths as you (and many others) assume, but any behavioral response at all. The permanent injury estimates were based on an exceedingly cautious level of exposure, if animals should be nearby (basically, they counted any beaked whale that might hear sonar as a potential injury, since they have, a few times, beached after fleeing moderate level sonar sounds). You were right in the main thrust of the NRDC case, which was that the Navy had not completed the required NEPA procedures (mainly an EIS). The eventual Supreme Court ruling, while very generous to the Navy (basically saying that whatever the Navy says they need should get extra weight in lower court proceedings, even perhaps outweighing objective looks at the facts), also did not question the underlying point that the Navy MUST comply with our nation's environmental laws. And, this and other cases did push the Navy to commence EIS processes for all domestic sonar training (though they still do not apply for permits for overseas training, or the far more common routine use of mid-frequency active sonar on hundreds of ships around the world). Beyond that, your answer makes it seem as though any time that sonar is used, whales are fleeing and injuring themselves. This is, make no mistake, a very annoying and unnatural sound, and animals do tend to avoid it. I haven't heard the "swimming hundreds of miles" to escape it report anywhere else, but smaller-scale avoidance is common. Strandings are, however, exceedingly rare (especially considering the thousands of times this sonar is used worldwide every year). Animals must be very close to be directly injured by the sound, though a range of possible escape behaviors are suspected to cause physiological injury in some cases; and, surely there are whales that are injured far at sea and drown, so strandings are not the only measure of the severe harm that may be caused. Many species seem to be affected (again, this is a really horrible sound), but very few strand. One minor quibble is that sound levels underwater have dB measures that are about 65dB louder than equivalent sound in air (due to the density of water); thus, the rock concert at 130dB would be measured at 195dB underwater. Still, mid-frequency active sonars are very very loud, and can be heard above the background noise for tens or perhaps a hundred kilometers. Your 140dB at 300km seems like a rare scenario; and, this would be the equivalent of 75dB in air, still generally audible, though, above the ocean's background level of 80-120dB). (a far less common low-frequency system, used at this point in the west Pacific, can be heard for a thousand kilometers or more). Finally, there are indeed several things that the Navy could do to minimize the risk of injury to marine mammals, as NRDC and others have stressed. Ramp-up of the sound may help, as would avoiding some especially important biological habitats (the Navy insists of having free reign everywhere within the existing Naval Training Ranges, with encompass most of the coastal waters of the continental US). From the Navy's perspective, they feel that they've been doing sonar training for decades with very few incidents, and such precautions are overkill. It should be noted that the Navy DOES use a clear set of precautions; they are not simply blasting away with no regard to whales. The current debate is over whether they could or should be doing more, at least in the controlled situations of their training exercises. No one, including the NRDC, has questioned the use of mid-frequency active sonar during normal operations at sea, where it is routinely used in many situations, including sweeping ahead of aircraft carriers, checking harbors before entering, and in some important shipping choke points between land masses. The Acoustic Ecology Institute covers all these issues in some depth; readers may enjoy some of our special reports, including two on sonar issues, available at http://AcousticEcology.org/specialreports.html Good try at answering a difficult question. I’m afraid you’re off on some of the technical facts, though. In California, Navy estimates were that their training mission would result in 170,000 “takes” of marine mammals; this is not deaths as you (and many others) assume, but any behavioral response at all. The permanent injury estimates were based on an exceedingly cautious level of exposure, if animals should be nearby (basically, they counted any beaked whale that might hear sonar as a potential injury, since they have, a few times, beached after fleeing moderate level sonar sounds). You were right in the main thrust of the NRDC case, which was that the Navy had not completed the required NEPA procedures (mainly an EIS). The eventual Supreme Court ruling, while very generous to the Navy (basically saying that whatever the Navy says they need should get extra weight in lower court proceedings, even perhaps outweighing objective looks at the facts), also did not question the underlying point that the Navy MUST comply with our nation’s environmental laws. And, this and other cases did push the Navy to commence EIS processes for all domestic sonar training (though they still do not apply for permits for overseas training, or the far more common routine use of mid-frequency active sonar on hundreds of ships around the world).

Beyond that, your answer makes it seem as though any time that sonar is used, whales are fleeing and injuring themselves. This is, make no mistake, a very annoying and unnatural sound, and animals do tend to avoid it. I haven’t heard the “swimming hundreds of miles” to escape it report anywhere else, but smaller-scale avoidance is common. Strandings are, however, exceedingly rare (especially considering the thousands of times this sonar is used worldwide every year). Animals must be very close to be directly injured by the sound, though a range of possible escape behaviors are suspected to cause physiological injury in some cases; and, surely there are whales that are injured far at sea and drown, so strandings are not the only measure of the severe harm that may be caused. Many species seem to be affected (again, this is a really horrible sound), but very few strand.

One minor quibble is that sound levels underwater have dB measures that are about 65dB louder than equivalent sound in air (due to the density of water); thus, the rock concert at 130dB would be measured at 195dB underwater. Still, mid-frequency active sonars are very very loud, and can be heard above the background noise for tens or perhaps a hundred kilometers. Your 140dB at 300km seems like a rare scenario; and, this would be the equivalent of 75dB in air, still generally audible, though, above the ocean’s background level of 80-120dB). (a far less common low-frequency system, used at this point in the west Pacific, can be heard for a thousand kilometers or more).

Finally, there are indeed several things that the Navy could do to minimize the risk of injury to marine mammals, as NRDC and others have stressed. Ramp-up of the sound may help, as would avoiding some especially important biological habitats (the Navy insists of having free reign everywhere within the existing Naval Training Ranges, with encompass most of the coastal waters of the continental US). From the Navy’s perspective, they feel that they’ve been doing sonar training for decades with very few incidents, and such precautions are overkill. It should be noted that the Navy DOES use a clear set of precautions; they are not simply blasting away with no regard to whales. The current debate is over whether they could or should be doing more, at least in the controlled situations of their training exercises. No one, including the NRDC, has questioned the use of mid-frequency active sonar during normal operations at sea, where it is routinely used in many situations, including sweeping ahead of aircraft carriers, checking harbors before entering, and in some important shipping choke points between land masses.

The Acoustic Ecology Institute covers all these issues in some depth; readers may enjoy some of our special reports, including two on sonar issues, available at http://AcousticEcology.org/specialreports.html

]]>