As reported by MSNBC:
Conservationists counted 615 dead dolphins along a 90-mile stretch of beaches in Peru, a wildlife group said Wednesday, and the leading suspect is acoustic testing offshore by oil companies.Photo via BoingBoing.
"If you can count 615 dead dolphins, you can be sure there are a great many more out at sea and the total will reach into the thousands,” Hardy Jones, head of the conservation group BlueVoice.org, said in a statement after he and an expert with ORCA Peru walked the beaches.
Indeed, the head of a local fishermen's association told Peru21.pe that he estimated more than 3,000 dolphins had died so far this year, based on what he saw in the water and on beaches.
BlueVoice.org stated that "initial tests ... show evidence of acoustical impact from sonic blasts used in exploration for oil." The ORCA Peru expert, veterinarian Carlos Yaipen Llanos, said that while "we have no definitive evidence," he suspects acoustic testing created a "marine bubble" -- in essence a sonic blast that led to internal bleeding, loss of equilibrium and disorientation.
BlueVoice.org noted that the U.S. has suspended similar testing in the Gulf of Mexico due to recent sightings of dead and sick dolphins. The ban was set to last through the dolphins' calving season, which ends in May.
I can't find anything about a sonic "marine bubble", a phrase that made me curious to understand the mechanics.
ReplyDeleteIt did lead me to learn more about anthropocentric sonic impact beneath the ocean surface. First task was to find my way past the hundreds of postings and re-postings of various versions of the story of these dolphin deaths in Peru, many rather hyperbolic.
There seems to be no serious disagreement that exploration drilling produces noise, as do many other human activities, though it's argued that exploration isn't as big a producer, a concern, as some other activities. Measurements as high as 180-220 decibels are possible, though it's interesting to note that the blue whale produces sounds as loud as 190 decibels, and other whales 170-180.
In this, as in any discussion, it's also useful to view this impact in context of other human impacts: WWF reports research indicating 1000 cetaceans (whales, dolphins, etc) drown in fish nets each day, more than 300,000 a year. (http://www.worldwildlife.org/who/media/press/2003/WWFPresitem625.html)
Minnesotastan, you spark so many interesting research forays for me =-)
embeetee, I agree with the lack of info available under the term "marine bubble" (or "sonic bubble"). The earliest use of that term I found was in a Peru Today publication that was probably translated from the Spanish.
DeleteFor more information on the topic in general, a better search term would be "acoustic trauma", which yields for example this article back in 2005 -
http://www.ens-newswire.com/ens/nov2005/2005-11-22-01.asp
or search sonar + death.
There's a lot out there if you can find it.
Thanks for that, Minnesotan, will read more. My note on context, however, is I believe important. Same goes for windmill towers, which take a big hit for bird deaths but actually are a very tiny source compared to others.
ReplyDeleteMy point here is, of course, not that we shouldn't care to try to reduce them, only that we can't lose perspective. We save perhaps hundreds of thousands of cetaceans by focusing on reducing fish net drownings, surely lower hanging fruit if our goal to is reduce the number of cetacean deaths caused by humans.
http://www.cbc.ca/news/world/story/2012/05/06/peru-beach-deaths.html
Dolphins thought at this point to be because of a virus.
Pelicans too, a funny coincidence (don't mean anything by that, simply saying what could affect both?)...but then, coincidences often are just that, nothing more than a statistical curiosity.
Yikes, typos, sorry:
DeleteMy point here is not, of course, that we [...]
We'd save perhaps [...]
I presume if they're sensitive to the sonar they'd tend to flee it, as we would flee loud noises. So wouldn't starting up a sonar session with ramping volume be a reasonable solution, given them time to move far enough to escape the discomfort and possible eventual damage? This is too simple an idea for it not to have been considered, so I would guess it has and found not helpful.
I'd assume that no other cetacean would want to be anywhere near a blue whale when it sounds off, either, at 190 dB.