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whales
``` The e-mail message about oceanographic noise experiments that has been passing around the net, and that I forwarded to RRE, has created some controversy. I've enclosed the nearest thing to an official rebuttal that I've found. In the interest of fairness, you might consider passing it along anyplace that you sent the original message.
Note that another version of this message has already been circulated widely on the net without the permission of its author. I've obtained the author's permission, and she has made some corrections.
Phil
Encl:
Date: Fri, 1 Apr 94 09:10:06 PST
From: "Susan Hautala"
Phil,
I am in no way an expert on this project, just an oceanographer at Scripps, summarizing the ATOC side of the story for friends who were asking, and am rather surprised to see it being distributed widely. But, it is fine with me if you forward my email (I made a couple of corrections to the enclosed text, so please use this version.) If you want more complete information, try the ATOC office at (619)-534-5671...I don't know of an email address for the office.
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Date: Tue, 29 Mar 94 17:36:53 PST
From: Susan Hautala
The scientists (spokesperson: Walter Munk) in charge of ATOC held an institution wide seminar today to respond to the recent uproar in press and email. This is my own distillation of their response. None of the hundred or so scientists in attendance had anything to say that would lead me to believe that their case is factually inaccurate.
Disclaimer: This is meant to clear up misconceptions. There are other real issues involving the value for $$ of the science and noise pollution in general in the ocean (everyday noise) and its effects on marine mammals which aren't being addressed by the flame debate.
There seem to be two major misconceptions
1. Concerning the decibel scale in the ocean. The numbers are different than those in air, both because of the difference in density and sound speed in the two media and because of a difference in choice of reference pressure. I.e.,
noise dB in air dB in water
normal speech 59 120 rock and roll 110 172 blue whale 188 ATOC source 195 cruise ship 205 underwater explosion 296
These are values if the listener is standing 1 meter from the sound source. The levels die off with distance...at 3m the ATOC source is comparable to a blue whale at 1 m, at 15 m it is down to rock and roll, at 30 km it has a sound level equivalent to normal speech. I quote a flyer distributed by Walter Munk: "Each ATOC source is equivalent to adding 5 blue whales or 1 large cruise ship to the ocean's noise background."
2. The second misconception is represented by this statement
I quote flame mail: "Scripps estimates its broadcasts off the California coast alone would result in a maximum potential "take" ... of 26,000 whales belonging to 10 species; 406,000 dolphins belonging to 8 species; and 245,000 seals, sea lions, and elephant seals. And that's during the FIRST YEAR of the experiment!"
This relates to the conditions of the permit that Scripps is applying for from NMFC. The permit would allow the program to "take" that number of marine mammals. "Take" has a very odd definition, involving not only killing marine mammals, but ALTERING THEIR BEHAVIOR by (possibly among other things) - causing a 30 degree or greater deviation in their course - causing them to stop communicating - causing them to change their breathing pattern.
On the advice of the NMFC permit office (apparently a standard practice) these numbers were designed to reflect the maximum number of animals that could possibly come into proximity with the sources . Since the experiment spans the Pacific (there are 2 sources, one in CA, one in Hawaii), these numbers represent the entire known population of the Pacific marine mammal community.
Some other points:
A pilot experiment was conducted at Heard Island in the Southern Ocean several years ago. A similar permit was obtained with similar strange numbers, this time reflecting the entire marine mammal populations of the Indian and Southern Oceans. Numerous whale biologists participated in that study and no injuries and even no negative effects on behavior were observed although several mammals ventured over to the source for a closer look, apparently out of curiosity. That source had a strength of 214 dB, was located at a depth of 175 meters and transmitted one hour out of every three. ATOC plans are for a 195 dB source at a depth of 3000 ft transmitting 20 minutes out of every 4 hours and possibly less frequently once the tidal variability is well understood.
Part of ATOC is a 2.9 Million Marine Mammal Research Program with participating scientists from several institutions to study the response of whales to the low frequency sound sources. I quote the flyer distributed by Walter Munk: "If any new evidence of adverse reactions of marine mammals to the ATOC sound sources is discovered by the Marine Mammal Research Program, immediate action will be taken to eliminate the effects." ```
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