Re: sonar effects in whale strandings
- From: "W. D. Allen Sr." <ballensr@xxxxxxxxxxxx>
- Date: Sat, 29 Oct 2005 10:21:33 -0700
level of decibels emitted it's the level received that's
harmful. Sound power diminishes as the square of the distance between
transmitter and receiver, plus a variety of other attenuation factors unique
to sea water.
Beware the educational caliber of journalists writing for today's "news"
media. Touting high decibel levels transmitted is emotionally inflammatory
but not intellectually illuminating in defining the "problem"!
end
"Jack Linthicum" <jacklinthicum@xxxxxxxxxxxxx> wrote in message
news:1130605356.852550.280280@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> Mark Test wrote:
>> "tony fleming" <tfleming1@xxxxxxxxxxxxx> wrote in message
>> news:1130585991.430195.29990@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> > i'm interested in any evidence for sonar effects upon mammals such as
>> > whales and dolpohins. what hard evidence exists?
>> >
>> Plenty of hard evidence exists that Low Freq sonar is harmless to
>> whales and other marine mammals, they've even "pinged" human divers
>> with LFA and the divers reprted no adverse effects.
>>
>> A Dr. Chris Clark and many others headed up the research...
>>
>> http://www.surtass-lfa-eis.com/Research/index.htm
>>
>> I haven't found much research regarding other sonars.
>>
>> Mark
>
> I would love watch you take 215-235 decibels, say as you walked out in
> the morning to get the paper or head for work. Nice little ear-blowing
> surprise.
> Actually, a blast of visible light would be more appropriate as whales
> guide themselves by sonar and humans by sight.
>
> http://www.nrdc.org/wildlife/marine/sonar.asp
>
> Active Sonar: How It Harms Marine Life
>
> Military active sonar works like a floodlight, emitting sound waves
> that sweep across tens or even hundreds of miles of ocean, revealing
> objects in their path. But that kind of power requires the use of
> extremely loud sound. Each loudspeaker in the LFA system's wide array,
> for example, can generate 215 decibels' worth -- sound as intense as
> that produced by a twin-engine fighter jet at takeoff. Some
> mid-frequency sonar systems can put out over 235 decibels, as loud as a
> Saturn V rocket at launch. One hundred miles from the LFA system, sound
> levels can approach 160 decibels, well beyond the Navy's own safety
> limits for humans.
>
> Evidence of the harm such a barrage of sound can do began to surface in
> March 2000, when members of four different species of whales stranded
> themselves on beaches in the Bahamas after a U.S. Navy battle group
> used active sonar in the area. Investigators found that the whales were
> bleeding internally around their brains and ears. Although the Navy
> initially denied responsibility, the government's investigation
> established with virtual certainty that the strandings were caused by
> its use of active sonar. Since the incident, the area's population of
> Cuvier's beaked whales has all but disappeared, leading researchers to
> conclude that they either abandoned their habitat or died at sea.
>
> The Bahamas, it turned out, was only the tip of an iceberg. Additional
> mass strandings and deaths associated with military activities and
> active sonar have occurred in Madeira (2000), Greece (1996), the U.S.
> Virgin Islands (1998, 1999), the Canary Islands (1985, 1988, 1989,
> 2002), and, most recently, the northwest coast of the United States
> (2003). And in July 2004 researchers uncovered an extraordinary
> concentration of whale strandings near Yokosuka, a major U.S. Navy base
> off the Pacific coast of Japan. The Navy's active sonar program appears
> to be responsible for many more whale strandings than had previously
> been imagined.
>
> How does active sonar harm whales? According to a recent report in the
> journal Nature, animals that came ashore during one mass stranding had
> developed large emboli, or bubbles, in their organ tissue. The report
> suggested that the animals had suffered from something akin to a severe
> case of "the bends" -- the illness that can kill scuba divers who
> surface too quickly from deep water. The study supports what many
> scientists have long suspected: that the whales stranded on shore are
> only the most visible symptom of a problem affecting much larger
> numbers of marine life.
>
> Other impacts, though more subtle, are no less serious. Marine mammals
> and many species of fish use sound to follow migratory routes, locate
> each other over great distances, find food and care for their young.
> Noise that undermines their ability to hear can threaten their ability
> to function and, over the long term, to survive. Naval sonar has been
> shown to alter the singing of humpback whales, an activity essential to
> the reproduction of this endangered species; to disrupt the feeding of
> orcas; and to cause porpoises and other species to leap from the water,
> or panic and flee. Over time, these effects could undermine the fitness
> of populations of animals, contributing to what prominent biologist
> Sylvia Earle has called "a death of a thousand cuts."
>
>
> Reining in LFA Sonar
>
> Since 1994, when NRDC began investigating rumors that sound experiments
> were taking place off the California coast, LFA (Low-frequency Active)
> sonar has been of particular concern because of the enormous distances
> traveled by its intense blasts of sound. During testing off the
> California coast, noise from a single LFA system was detected across
> the breadth of the North Pacific. By the Navy's own estimates, even 300
> miles from the source these sonic waves can retain an intensity of 140
> decibels -- still a hundred times more intense than the noise aversion
> threshold for gray whales. Many scientists believe that blanketing the
> oceans with such deafening sound could harm entire populations of
> whales, dolphins and fish.
>
> NRDC's decade-long campaign to expose the dangers of active sonar won a
> major victory in August 2003, when a federal court ruled illegal the
> Navy's plan to deploy LFA sonar through 75 percent of the world's
> oceans. On the heels of this ruling, the Navy agreed to limit use of
> the system to a fraction of the area originally proposed, and that use
> of LFA sonar will be guided by negotiated geographical limits and
> seasonal exclusions; conservationists believe this will protect
> critical habitat and whale migrations. None of the limits apply during
> war or heightened threat conditions; the Navy also retains the
> flexibility it needs for training exercises. The pact demonstrates that
> current law can safeguard both the environment and national security.
>
> http://www.cdnn.info/news/eco/e051019.html
>
> The association between sonar and whale mortalities is "very convincing
> and appears overwhelming," according to a report issued last year by
> the whale biologists who make up the scientific committee of the
> International Whaling Commission.
>
> The document concluded with 22 recommendations involving the use of
> high-intensity, mid-frequency military sonar, seismic oil and gas
> surveying, possible mitigation measures, and increased multi-national
> research efforts.
>
> This detailed concern for noise pollution in the marine environment was
> unprecedented at the IWC and it may signal rising global awareness of
> the harmful effects of loud, underwater noise.
>
> "Military sonar needlessly threatens whole populations of whales and
> other marine animals," said Joel Reynolds, a senior attorney at NRDC.
> "In violation of our environmental laws, the Navy refuses to take basic
> precautions that could spare these majestic creatures. Now we're asking
> the courts to enforce those laws."
>
> Mass stranding and mortality events associated with mid-frequency sonar
> exercises have occurred, among other places, in North Carolina (2005);
> Haro Strait off the coast of Washington State (2003); the Canary
> Islands (2004, 2002, 1989, 1986, 1985); Madeira (2000); the U.S. Virgin
> Islands (1999, 1998); and in Greece (1996). One of the best documented
> incidents occurred in the Bahamas in 2000 when 16 whales of three
> species stranded along 150 miles of shoreline as ships blasted the area
> with sonar.
>
> The U.S. Navy later acknowledged in an official report that its use of
> sonar was the likely cause of the stranding.
>
> Scientists at several major universities, working under federal
> contract, conducted necropsies and tissue analyses on the whales to
> determine why they died. The government has refused to release the
> scientists' findings despite a Freedom of Information Act (FOIA)
> lawsuit filed by NRDC in June.
>
.
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