beached whales got bent avoiding sonar

[veek]

This is the first time I've heard of this, but it appears that there is now evidence from beached whales that sonar may cause some whales to dive and surface to avoid the noise...

From Nature, vol. 440, 30 March 2006, p. 593:

"More whale strandings are linked to sonar

Examinations of four whales found stranded along the Spanish coast in January seem to confirm a 2003 Nature report linking sonar to the deaths of several beaked whales.

In recent years, naval sonar devices have been the suspected cause of an increasing number of whale strandings worldwide. The whales are thought to take evasive action to avoid the noise, sometimes diving and surfacing until they suffer decompression sickness and die.

In 2003, British and Spanish researchers reported that Cuvier's beaked whales (Ziphius cavirostris), stranded off the Canary Islands the previous year, had deadly gas-bubble lesions called emboli in their livers. They suggested these were caused by decompression (P. D. Jepson et al. Nature 425, 575-576; 2003).

After a group of beaked whales went ashore in January, along Spain's Costa del Sol, the Spanish Cetacean Society in Madred called veterinarian Antonio Fernandez to perform necropsies on four of the animals. He and his colleagues from the University of Las Palmas de Gran Canaria found the same embolic syndrome as that found in the 2003 study.

"This is the first confirmation of the 2003 report," says veterinarian Paul Jepson of the Zoological Society of London, lead author of that article. The new findings are expected to be published in the coming months.

Officials at the Cetacean Society suspect that mid-frequency naval sonar caused the strandings. But Fernandez notes that the ships that might have been responsibile have not been identified.

Earlier this month, about 45 pilot whales died after stranding on the western side of the island of Sulawesi in Indonesia, following joint US and Indonesian naval exercises in the nearby Macassar Strait. The cause of the stranding is under investigation.

Some US Navy officials, and oceanographers who use devices to generate air bursts underwater for seismic studies, have been accused of blocking efforts to uncover the links between noise and whale strandings (see Nature 439, 376-377; 2006).

Rex Dalton"

[archman]

Most reports coming out of Nature or Science are highly preliminary, which the media does not seem to understand.

So wait for the full-blown article to come out.

[roturner]

Most reports coming out of Nature or Science are highly preliminary, which the media does not seem to understand.

So wait for the full-blown article to come out.


Come on Archman....even the bloody navy admits that the high-volume low-frequency sonar is the death ray of the sea....they don't plan on actually *doing* anything about it but by now we can accept this as common knowledge...

Sheesh.

R..

[Kray_Z]

beaked or beach.. not quite sure what was meant there becuase beached would fit in its spot but beaked whales exist :S any insight?

[MALTA_DIVER]

How do these whales get bent by breathing air at sea level only?? Do they breath compressed gas at lower levels?? I have no dout they stranded due to sonar but getting bent is a little far fetched. Where is Dr. Decompression when you need him?
These whale are able to dive thousands of feet deep with no problem with great repitition.
Unless Im missing something about free divers getting bent but have never heard of that.

[roturner]

How do these whales get bent by breathing air at sea level only?? Do they breath compressed gas at lower levels?? I have no dout they stranded due to sonar but getting bent is a little far fetched. Where is Dr. Decompression when you need him?
These whale are able to dive thousands of feet deep with no problem with great repitition.
Unless Im missing something about free divers getting bent but have never heard of that.

Think of whales as extreme free-divers. The physiology is very different but when you're freediving at 100m for 20 min there is compressed gas .... in the lungs.

A human free-diver would have a similar problem if they could stay underwater long enough.

R..

[archman]

Come on Archman....even the bloody navy admits that the high-volume low-frequency sonar is the death ray of the sea....they don't plan on actually *doing* anything about it but by now we can accept this as common knowledge...

Quite the contrary, in fact. The U.S. Navy has performed the most comprehensive study of this by far. It’s endorsed by NOAA and their NMFS subsidiary. Their results put a stopper over a lot of the media rhetoric. Oddly, I have found that hardly anyone (including marine mammalogists) is even aware of these NMFS-approved studies, much less have read them. They have a lovely website too, but nobody ever visits it.
http://www.surtass-lfa-eis.com/

Despite all the hooplah, there is very little quantifiable data to support most of the claims from environmentalists. It's primarily ancedotal reporting and coincidental conjecture. I've been keeping close tabs on this for a few years, now. On three occasions I've actually had to forward these studies to colleagues who actually WORK in this field. They were blissfully ignorant, which is... highly unprofessional.

The NOAA 2002 final ruling report can be accessed from this link
The comments and response sections starting on p. 46719 are a great read.
http://www.nmfs.noaa.gov/prot_res/readingrm/MMSURTASS/lfasonar_fr02.pdf


Here’s a graphic summary of the original study. Also ignored by most anti-sonar websites.
http://www.surtass-lfa-eis.com/Research/index.htm

This Q&A dispenses most of the commonly regurgitated sonar myths seen online and in magazines.
http://www.surtass-lfa-eis.com/FAQ/index.htm

Here’s a listing of most of the public outreach work performed by the Navy, from which many of the 2002 final ruling questions originated.

http://www.surtass-lfa-eis.com/EIA/index.htm

People can always argue the merits of a study sponsored by the Navy, but I ask such critics to read the reports and back up their claims first.

[OutdoorStud]

How do these whales get bent by breathing air at sea level only?? Do they breath compressed gas at lower levels?? I have no dout they stranded due to sonar but getting bent is a little far fetched. Where is Dr. Decompression when you need him?
These whale are able to dive thousands of feet deep with no problem with great repitition.
Unless Im missing something about free divers getting bent but have never heard of that.
Human freedivers can get dcs symptoms, ama divers, who are proffesional asiatic free divers have reported dcs symptoms to studies on it, the conclusion was they are getting dcs but do not report it.

[usnadiver03]

Has anyone asked the whales how they feel?

[Jai Bar]

How do these whales get bent by breathing air at sea level only?? Do they breath compressed gas at lower levels?? I have no dout they stranded due to sonar but getting bent is a little far fetched. Where is Dr. Decompression when you need him?
These whale are able to dive thousands of feet deep with no problem with great repitition.
Unless Im missing something about free divers getting bent but have never heard of that.

I don't think that the whales get DCS "naturally". However, exposure to high intensity ultrasound such as sonar can create bubbles (from the dissolved gas in tissues), induce cavitation etc. Not only in whales- at certain ultrasound levels it can also occur in humans who never dived, at sea level :05:

It is something like this: Tissues have a certain amount of dissolved gasses, the cause of breathing air, whether at sea level or depth there is always dissolved gas.
A sonar/ultrasound wave can be considered as a pressure wave propagating at the speed of sound. When it passes through tissue, there is a compression of the particles, immediately followed by a decompression as the wave passes. In some sonars or ultrasound systems this cicle is repeated hundred of thousands of times each second. These sudden changes in pressure can be strong enough to cause bubbles and cavitation within tissues, and at certain levels they can cause violent damage.

Of course, it depends on many factors such as ultrasound intensity to begin with, distance from source, beam shape etc. etc. etc. But the bottom line is that in *some* circumstances, sonar can be harmful to whales, as well as humans or anything in the water which has dissolved gasses. I guess that this rarely happens, though.

[JonAustin]

Human freedivers can get dcs symptoms, ama divers, who are proffesional asiatic free divers have reported dcs symptoms to studies on it, the conclusion was they are getting dcs but do not report it.

Right, but these are whales. In contrast to human divers, whales exhale almost all of the air out of their lungs, prior to diving. Among other adaptations, they use the oxygen reserves in their blood (they proportionately have a lot more hemoglobin than humans), rather than what's in their lungs.

With little or no air in their lungs, there's nothing to compress. Therefore, there is no increased partial pressure. Therefore there is no nitrogen dissolution. Therefore there can be no nitrogen coming out of solution. Therefore there is no DCS or arterial gas embolism.

I'm certainly no marine biologist, but color me skeptical about this article.

[archman]

Actually, there is a highly interesting article that supports naturally occurring decompression illness in whales. Hmm... let me see if I find a link.

http://www.whoi.edu/oceanus/viewArticle.do?id=4720

You gotta love those photos.

[roturner]

Quite the contrary, in fact. The U.S. Navy has performed the most comprehensive study of this by far. It’s endorsed by NOAA and their NMFS subsidiary. Their results put a stopper over a lot of the media rhetoric. Oddly, I have found that hardly anyone (including marine mammalogists) is even aware of these NMFS-approved studies, much less have read them. They have a lovely website too, but nobody ever visits it.
http://www.surtass-lfa-eis.com/

Despite all the hooplah, there is very little quantifiable data to support most of the claims from environmentalists. It's primarily ancedotal reporting and coincidental conjecture. I've been keeping close tabs on this for a few years, now. On three occasions I've actually had to forward these studies to colleagues who actually WORK in this field. They were blissfully ignorant, which is... highly unprofessional.

The NOAA 2002 final ruling report can be accessed from this link
The comments and response sections starting on p. 46719 are a great read.
http://www.nmfs.noaa.gov/prot_res/readingrm/MMSURTASS/lfasonar_fr02.pdf


Here’s a graphic summary of the original study. Also ignored by most anti-sonar websites.
http://www.surtass-lfa-eis.com/Research/index.htm

This Q&A dispenses most of the commonly regurgitated sonar myths seen online and in magazines.
http://www.surtass-lfa-eis.com/FAQ/index.htm

Here’s a listing of most of the public outreach work performed by the Navy, from which many of the 2002 final ruling questions originated.

http://www.surtass-lfa-eis.com/EIA/index.htm

People can always argue the merits of a study sponsored by the Navy, but I ask such critics to read the reports and back up their claims first.

I need to take some time to read this before I respond further. I clearly recall reading a statement from the Navy after the pilot whale incident in the Caribbean that basically said that they thought the sonar was the cause. IIRC the statement also said that it needed to be researched. I guess that's happened now and they're back to denying it..... It's going to be hard to not be skeptical about the results given the sponsor but I'll do my best.

R..

[archman]

I clearly recall reading a statement from the Navy after the pilot whale incident in the Caribbean that basically said that they thought the sonar was the cause. IIRC the statement also said that it needed to be researched.

If you can give me the year of the beaching, and the exact location (Bahamas?), I can track it down for you. NOAA's got everything posted online, it's just tricky finding some stuff.

[roturner]

If you can give me the year of the beaching, and the exact location (Bahamas?), I can track it down for you. NOAA's got everything posted online, it's just tricky finding some stuff.

My memory isn't that accurate. Can you use a date-range?

R..

[archman]

The problem is its pilot whales. These things strand for a nothing, all the time. There are TONS of incident reports worldwide to pore over.

[Humuhumunukunukuapua'a]

How do these whales get bent by breathing air at sea level only?? Do they breath compressed gas at lower levels?? I have no dout they stranded due to sonar but getting bent is a little far fetched. Where is Dr. Decompression when you need him?
These whale are able to dive thousands of feet deep with no problem with great repitition.
Unless Im missing something about free divers getting bent but have never heard of that.

I think you're confusing lung over-expansion and getting bent. You are safe from lung overexpansion if you breathe air at the surface, descend, then ascend. You risk lung overexpansion if you breathe a volume of air at depth, hold your breath, and ascend.

The bends don't have anything to do with compressed air per se. The air in your lungs is under pressure greater than surface level, so your body absorbs more Nitrogen from the air in your lungs. So if you can stay down long enough or go deep enough, you can absorb a lot of extra Nitrogen. Then, if you ascend too quickly, bubbles form and you get bent.

Also, the way I understand the whale issue, it's not the sonar making bubbles in the whales (or maybe that's part of it too.) But an article I read (in the DAN magazine I think?) said that whales definitely do get DCS symptoms naturally. The bones of old Sperm Whales show pitting at the joints that scientists attribute to Nitrogen bubbles.

The concern with sonar as presented in this article was that the sonar makes the whales ascend much faster than usual to avoid the sonar. Thus they get badly bent. Maybe the "sonar making bubbles" phenomenon is real too, but I don't know anything about that. The explanation I had was much simpler. The whales are basically being "startled" into ascending much too quickly and they get bent because of the enormous depths and long times that they dive.

[archman]

Dang pilot whales... is it this one?

http://www.cbsnews.com/stories/2003/11/25/tech/main585590.shtml

[roturner]

The problem is its pilot whales. These things strand for a nothing, all the time. There are TONS of incident reports worldwide to pore over.

What I recall is that the incident occured immediately after a test of that big-asss low frequency sonar. The test involved several ships and I don't remember the location but it might have been the Bahama's. If memory serves *no* whales were spotted in the entire region for a period of weeks or possibly months after the incident, leading to speculation that they had fled and the Navy admitted it might have had something to do with the sonar because a number (maybe all) of the whales were bleeding from their eyes and had serious internal trauma, possibly to the ears (or whatever it is that whales have). I think it was in 1999 but it might have been earlier. Try 1998-2001.

Is that enough to go on?

R..

[roturner]

Dang pilot whales... is it this one?

http://www.cbsnews.com/stories/2003/11/25/tech/main585590.shtml

We crossed posts. No it doesn't sound like the same incident.

R..

[archman]

Oh! If it's late 1990's then it falls under the LOFAR research study. I'll find it and post some links.

[Humuhumunukunukuapua'a]

With little or no air in their lungs, there's nothing to compress. Therefore, there is no increased partial pressure. Therefore there is no nitrogen dissolution. Therefore there can be no nitrogen coming out of solution. Therefore there is no DCS or arterial gas embolism.

Little air, maybe...but they definitely have some air in their lungs. There seems to be a lot of thinking lately that suggests whales do suffer from long term damage from DCS type effects of Nitrogen bubbles. The link below mentions a study on really old bones from well before the use of sonar that showed the same pitting from bubbles that scientists are finding now. The older the whale, the more severe the damage.

Check out this link..it's interesting:
http://news.bbc.co.uk/2/hi/science/nature/4122119.stm

Here's a clip:



They noticed that many of the bones contained lesions and pits, indicating the whales may have suffered mild, but chronic, decompression sickness over the course of their lives.


Anyway, sonar aside, I think it's becoming increasingly apparent to science that whales are, in fact, susceptible to DCS-like symptoms caused by dissolved nitrogen in blood and tissues.

Cheers :D

[archman]

Well, I’ve done some hunting. Everything I’ve found keep leading back to the multi-species Bahamian stranding event in March 2000. No pilot whales, however. This is the most exhaustively studied stranding event ever undertaken, and it’s also the report most often misquoted and misinterpreted by the media and various NGO’s. That’s due to the report’s findings lending credence to a tactical sonar exercise as the most logical culprit. The fruitcake media clung to that bit like a golden talisman, and have been weaving tall tales about it ever since.

But for those that actually read the details, there were a great many extenuating circumstances. Most environmentalists don’t really understand sonar, or marine mammals, for that matter. But NOAA and their scientists do.

The full blown joint Navy-NOAA report can be viewed here.
http://www.nmfs.noaa.gov/prot_res/overview/Interim_Bahamas_Report.pdf

And there’s also a extensive public comment and response section regarding it and other cetacean strandings that starts on p. 46724 of the 2002 NOAA ruling on LOFAR sonar. The questions asked are very good.
http://www.nmfs.noaa.gov/prot_res/readingrm/MMSURTASS/lfasonar_fr02.pdf

[Rickg]

What I recall is that the incident occured immediately after a test of that big-asss low frequency sonar. The test involved several ships and I don't remember the location but it might have been the Bahama's. If memory serves *no* whales were spotted in the entire region for a period of weeks or possibly months after the incident, leading to speculation that they had fled and the Navy admitted it might have had something to do with the sonar because a number (maybe all) of the whales were bleeding from their eyes and had serious internal trauma, possibly to the ears (or whatever it is that whales have). I think it was in 1999 but it might have been earlier. Try 1998-2001.

Is that enough to go on?

R..

roturner,

1. I believe this is the article that you are describing that occurred in 2000.

http://www.usatoday.com/news/science/biology/2001-12-21-beached-whale.htm

2. Here is a link to a an interim report on the stranding. I imagine the final report might also be available online.

http://www.nmfs.noaa.gov/pr/overview/Interim_Bahamas_Report.pdf

2. And if by "that big-asss low frequency sonar" you are referring to is the Navy's LFA system it was physically impossible for that system to have been involved because the ship was in the Pacific Ocean when this incident occurred and has been continually in the Pacific Ocean since some time in '97 if I remember right.

Rickg

[roturner]

OK, I'll take the time to read some of this stuff and get back to you.

R..

[MALTA_DIVER]

OK this is getting good!!
I think that the cause of the stranding caused by sonar is still up in the air?
however,
I still not convinced that whales/marine mammals can get bent. Have we looked in to Sea Lions, Orcas(I HATE these guys!!) for clues of the bends? What about Emperor penguins also extreme free divers?
I also remember watching Orcas in Antarctica exhaling before they dive. So would that reduce the amount of nitrogen in the blood for later expansion in the tissues.
I know that whales can live for a very long time!! We are are not sure how long in fact. I know some Pacific Northern Right whales have been found with very old harpoon heads in them. IF I remember right some have been found with stone points in them (National Geographic) Could this pitting of bones just be old age? Gout can do the same thing. Have diving whale bones been compared to whales that don't dive deep(baleen whales)
I'm VERY interested in these threads and would love to learn more about Marine Mammals
Malta_Diver

[Jai Bar]

OK this is getting good!!
Could this pitting of bones just be old age? Gout can do the same thing.


I suppose that whales suffer from old age just like any other animal on the planet. Whatever causes bone damage in humans may also cause similar effects on other animal's bones.

[JonAustin]

Thanks, archman and Humu(etc.)--I stand corrected. I'd be very interested to know the process by which they get DCS/embolisms, since they do have so little air available to cause it.

I did have to laugh at this part of the article referenced by archman:

"Their inventory included whales from the Pacific and Atlantic, and whales that died as long as 111 years ago—so the newly found phenomenon is neither localized nor recent.

The scientists theorize that the whales normally manage their surfacing behavior to decompression problems. ... But if a noxious sound—from a sonar, for instance, or seismic airguns used in oil exploration—disrupts their usual behavior and provokes fast surfacing, the whales risk acute problems from nitrogen emboli."

If whales had DCS/embolism symptoms over a century ago, and sonar is only about 60 years old, it seems like a bit of a leap to say that sonar is causing DCS/emboli. Now ear damage, I could totally understand.

[Santa]

Dang pilot whales...


Pilot whale. Stupid name for a creature that fails to steer clear of entire continents.

[JonAustin]

Perhaps the name was intended to be ironic?

[JonAustin]

Guess not:

Noun 1. pilot whale

pilot whale - small dark-colored whale of the Atlantic coast of the United States; the largest male acts as pilot or leader for the school

http://www.thefreedictionary.com/dict.asp?Word=pilot+whale

[Rickg]

1. I went on line to see if I could find a NOAA final report on the Bahamas Marine Mammal Stranding but couldn't find one. What I did find is this US Navy site where they discuss:

http://www.whalesandsonar.navy.mil/stranding_events.htm

"The Navy and NOAA Fisheries learned from the Bahamas stranding that certain marine mammals, particularly beaked whales, may be sensitive to mid-frequency sonar."

The site also discusses Navy-funded research and protective measures the Navy is taking to prevent a similar occurrence in the future.

2. If you read the interim report that I posted previously you will see that they believe a mid-frequency sonar (not LFA) being operated for an extended period of time (ASW exercise) in a confined space (channels between islands) also occupied by the marine mammals contributed to this stranding.

Rickg

[cerich]

Quite the contrary, in fact. The U.S. Navy has performed the most comprehensive study of this by far. It’s endorsed by NOAA and their NMFS subsidiary. Their results put a stopper over a lot of the media rhetoric. Oddly, I have found that hardly anyone (including marine mammalogists) is even aware of these NMFS-approved studies, much less have read them. They have a lovely website too, but nobody ever visits it.
http://www.surtass-lfa-eis.com/

Despite all the hooplah, there is very little quantifiable data to support most of the claims from environmentalists. It's primarily ancedotal reporting and coincidental conjecture. I've been keeping close tabs on this for a few years, now. On three occasions I've actually had to forward these studies to colleagues who actually WORK in this field. They were blissfully ignorant, which is... highly unprofessional.

The NOAA 2002 final ruling report can be accessed from this link
The comments and response sections starting on p. 46719 are a great read.
http://www.nmfs.noaa.gov/prot_res/readingrm/MMSURTASS/lfasonar_fr02.pdf


Here’s a graphic summary of the original study. Also ignored by most anti-sonar websites.
http://www.surtass-lfa-eis.com/Research/index.htm

This Q&A dispenses most of the commonly regurgitated sonar myths seen online and in magazines.
http://www.surtass-lfa-eis.com/FAQ/index.htm

Here’s a listing of most of the public outreach work performed by the Navy, from which many of the 2002 final ruling questions originated.

http://www.surtass-lfa-eis.com/EIA/index.htm

People can always argue the merits of a study sponsored by the Navy, but I ask such critics to read the reports and back up their claims first.

Then ask the Navy why it is SOP to use sonar as an anti Diver defensive mode? Because it is powerfull enough to kill them! Waters reaches a boil at the transducer on some sonars.

I can't imagine the whales enjoy it.

I'm generally not a die hard enviornmental issue type guy and having served in Submarines in the navy see that the sonar is needed, but to think it has no impact on the sea life is just garbage.

[E_mcSCOW]

.

[archman]

Then ask the Navy why it is SOP to use sonar as an anti Diver defensive mode? Because it is powerfull enough to kill them! Waters reaches a boil at the transducer on some sonars.

I can't imagine the whales enjoy it.

I'm generally not a die hard enviornmental issue type guy and having served in Submarines in the navy see that the sonar is needed, but to think it has no impact on the sea life is just garbage.

You didn't read any of those articles, apparently. There are extensive discussions of sonar types, frequencies, ranges, and what levels are believed to cause direct tissue damage. The Navy likes to use 180 decibels as a common benchmark.

[DivePartner1]

Well, I’ve done some hunting. Everything I’ve found keep leading back to the multi-species Bahamian stranding event in March 2000. No pilot whales, however. This is the most exhaustively studied stranding event ever undertaken, and it’s also the report most often misquoted and misinterpreted by the media and various NGO’s. That’s due to the report’s findings lending credence to a tactical sonar exercise as the most logical culprit. The fruitcake media clung to that bit like a golden talisman, and have been weaving tall tales about it ever since.

. . . .
http://www.nmfs.noaa.gov/prot_res/readingrm/MMSURTASS/lfasonar_fr02.pdf

Good detective work Arch.

The Navy's dilemma is that by honestly acknowledging harm under the unique circumstances of the Bahamas Report (noisy ASW fleet exercise catching deep diving whales in the shallows) they opened the Pandora's Box of inviting blame anytime a whale beaches in different, unrelated circumstances.

I believe the Bahamas incident involved beaked whales, not pilot whales. Pilot whales and others beached themselves before sonar existed, they still do and probably always will for reasons that we may some day better understand.

Blaming all groundings on the Navy without rigorous, objective, unbaised study of the cause of individual incidents does nothing to enhance this understanding of why whales do this.

[archman]

I have noticed that over the last decade, whenever a marine mammal beaching occurs, media reports tend to implicate any nearby military naval activity through association. Spanish navy, Canadian navy, US Navy... these are just ones off the top of my head that I've seen reported. Except for the Bahamian incident, I do not believe a single one of these accusations has ever been substantiated.

Merely by stating that naval vessels were in the area, news media places the assumption of causality into the minds of the public. If done repetitively without check (which it has for several years for this case), such behaviour can confuse peoples' ability to differentiate fact from theory.

[roturner]

Well,

I just typed in a lengthy response to this but lost it when my browser took a nap....

here's the summary of my conclusions:

1) the technology itself wouldn't appear to be inherently damaging to marine life

2) however, they play it too loud. The Navy determined a maximum safe operating volume of 190db, but they're typically playing it at 215 (300-odd times louder) and it has an operational capability of at least 240db, which is 100,000 times louder than they determined is "safe".

It would also appear that bottom topology and depth can have an affect. I guess that means that if it's echoing off the bottom that it can have an amplifying effect. That's not a surprise but it's worrying in the sense that they don't really have a good idea of what the total generated volume will be if it's used in shallow water. This could have been one of the issues a play in the Bahama's. In the Bahama's incident, there were several ships and the sonar was played at a maximum of 235 decibels in relatively shallow water. Worst of all worlds.

And here's what they said about the incident in the Bahama's


Based on the way in which the strandings coincided with ongoing naval activity involving tactical mid-range frequency sonar use in terms of both time and geography, the nature of the physiological effects experienced by the dead animals, and the absence of any other acoustic sources, the investigation team concludes that tactical mid-range frequency sonars aboard U.S. Navy ships that were in use during the sonar exercise in question were the most plausible source of this acoustic or impulse trauma.


That's an honest assessment and it wasn't written by the media.

It's easy to give the media the blame for it and I'm sure that perceptions of it being a bigger problem than it is might be realated to media exposure, but I would submit that without media exposure, the government's response to this issue may have been slower--or non existent. Bad media coverage or not, the conclusions are out there. Even by the Navy's own research, they're playing the system at unsafe volumes and as a result it *can* harm whales *if* they are close enough to the source of the sound.

It doesn't seem to me like it's an earth-shaking problem, though. The Navy appears to understand the issues and they appear to be acting responsibly in response. What I would still like to know, however is why they don't just play the system at 190db if they know that this is the safe limit..... I couldn't find any information about why they choose not to do this.

One more point; I was prepared to be very skeptical of the research but it would appear to be a lot more balanced than I was expecting.

R..

[archman]

Two major reasons why navies aren't too sorry, range and use.

It's mostly due to range. The noisy mid and high-frequency sonars don't travel very far underwater, unless there's unusual acoustic conditions.

The reason that active sonars operate at such high powers is linked to maximum effective range, just like radar. If you want a good max range, you're going to have to crank out more power. Ever wonder why aircraft and fixed radars have "stand clear!" warnings around them? A strong radar set can fry near-flying birds out of the sky. But the radiation intensity rapidly attenuates with distance, excepting steered beam types.

But unlike radar, active sonar is rarely used by naval vessels, even during wartime. It gives your position away. Most navies place far more emphasis on using passive sonar systems, which don't project sound. They only listen. And that doesn't harm marine life one bit.

The general public has the impression that navy sonars are primarily active types that ping away 24/7, and greatly exaggerate the effective ranges of active sonar. This is a gross mistake.

[Santa]

LOL, sure.

(In the slightly annoyed and slightly contemptful voice of Homer Simpson):
Tsch! "Pilot" whale.

[dbg40]

Most reports coming out of Nature or Science are highly preliminary, which the media does not seem to understand.

So wait for the full-blown article to come out.

I may add that they are "suspect" as well ,full blown article or not. While bashing the United States, and our military, is the newest fad worldwide, and all the cool kids are doing it from places that are not currently under attack by lunatics.... but that's another story....... Im not so fast to jump to any conclusions about this new brainchild of "science". Sea mammals have been involved in this behavior for a long time, and I have seen no concrete evidence that any one thing is the cause, including the evil US government. Do we ever do anything besides murder and pillage the earth and it's inhabitants??

[roturner]

Sea mammals have been involved in this behavior for a long time, and I have seen no concrete evidence that any one thing is the cause, including the evil US government.

Nobody could seriously suggest that this is the only cause but there is concrete evidence linking high volume sonars to *some* events.

R..

[riddler]

I still not convinced that whales/marine mammals can get bent.

It seems like there are two issues in this one thread - maybe they should be broken out into two threads:

1. Can whales get DCS? I don't know why it's so hard to believe. It's the same physics that applies to divers, and although our physiology is different, so is our capacity for deep diving. Breathing compressed air is not necessarily relevant. If a human could take a single breathe of air, dive to 2000 feet and stay down there for 45 minutes, then he/she is at risk for DCS, depending on how fast he/she comes up. Dive Training magazine has an article last year about DCS in whales. Scientists showed that deep diving whales have bone degradation that is consistant with DCS. They theorized that the whale brain has a pretty sophisticated "dive computer" inside it that tells the whale what a reasonable rate of ascension is, based on their dive profile. That's not so hard to believe, considering these creatures evolved to be able to do just that. Older whales were more likely to show evidence of past DCS trauma, suggesting that in their longer lives, they made more mistakes or took more risks while diving. If a whale gets DCS, they've dived too deep, for too long, followed by a rapid acsension (or at least too rapid for that dive). Maybe that particular giant squid that lived kinda deep looked so juicy, they couldn't help themselves ;)

2. Does SONAR cause DCS in whales? I think this one is a stretch - it's possible, but it would be very difficult to prove. You would have to tag a whale, get it to dive deep, then blast it with sonar to see if it scares the poor beast to a rapid ascension. Either that, or cage it and do doppler studies of SONAR on their very tissue while blasting it with SONAR. Either way, it's an invasive study.

Environmentalism is valid and necessary, but sometimes environmentalists go a little too far with pseudo-science and conjecture. I'd like to see more funding of environmental research so that we can show hard evidence of what is really going on, and then we can figure out how to solve the problem.