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This is something of a frivolous topic, but I'll bite. The sound
described in the query could very likely be from dolphins, instead of fish.
Although I do not study dolphins, I have frequently heard dolphins make a
sound that can't be better described than as like a squeaky door. As I
remember, the sound increases in volume then falls off suddenly (like a
squeaky door reaching the frame). I used the squeaky door analogy to tell
others what to listen for, when I ask them if they want to hear the dolphin
sounds.
One caveat is that I hear this sound while tracking fish tagged with
acoustic, ultrasonic transmitter tags, and I hear it through the headphones
connected to a wide band ultrasonic receiver connected to directional
hydrophones. By definition, the receiver would probably not be picking up
audible frequency sounds, like those that the kayaker's report. However, I
am not sure of the characteristics of the receivers (Sonotronics USR 5W)
with regard to audible range sounds. More likely, the squeaky door dolphin
sounds picked up by the receivers are high-frequency overtones of the
powerful audible-range sounds that the kayakers can hear.
Perhaps the inquirer should ask dolphin biologists about this, instead of
fish scientists. If he does, I would point out that the squeaky door sound
is made by an offshore dolphin species (don't know my dolphin species --
sorry), and the common inshore bottlenose dolphin sound does not always
resemble that of a squeaky door.
Randy
Randy E. Edwards, Ph.D.
Research Fish Ecologist
University of South Florida, College of Marine Science
USGS Center For Coastal & Watershed Studies
600 Fourth Street South
St. Petersburg, FL 33701-4846
Phone: 727/803-8747 (x3069)
FAX: 727/803-2031
[log in to unmask]
Do not tell fish stories where the people know you; but particularly, don't
tell them where they know the fish. [Mark Twain]
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