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    Re: [navigation] Noisy Sea Surface
    From: John Kabel
    Date: 2003 Nov 14, 14:18 -0500

    The other night on Daily Planet (see text and video clips on www.exn.ca)
    they talked about a strange popping or scratching sound that herring make
    in schools.  This seems to be mainly at night.  It is caused by release of
    gas from the swim bladder, through a duct connecting the bladder to the
    anus of the fish.  It occurs when the school changes depth in the water.
    It sounds a bit like a ticking.  When the fish are in large numbers, it
    could be a scratching sound, presumably.
    
    They did not say if other fish make this sound.  And it is not "intestinal
    gas" in the mammalian four-lettered sense of the word!!
    
    John Kabel
    London, Ontario
    
    > On Nov 14, 2003, at 5:56 AM, Fred Hebard wrote:
    >
    > > But why is it that disturbance of water leads to phosphorescence?  That
    > > would be an interesting, albeit off topic, question to address to the
    > > planktonologists (sic) at your wife's research station.
    >
    > Interesting question indeed.  We see much phosphorescence here in Puget
    > Sound at night in our plankton rich waters.
    >
    > I just returned from a wonderful 3 week trip delivering a boat from
    > Solomons, Maryland to Fort Pierce, Florida, a 1,000 nautical mile trip,
    > mostly done in the Intercoastal Waterway (ICW).  I highly recommend
    > this trip!  We anchored most nights, but occasionally stayed in
    > marinas.  We proceeded at about 60 nmi per day, at an average of 7
    > knots.
    >
    > Anyway, in Florida one night at a dock in St. Augustine, we HEARD the
    > strangest sounds coming through our hull.  Out of 20 nights sleeping
    > aboard our vessel (a 39' Krogen trawler), only at this one place did we
    > hear these strange sounds.  I got out of the boat and stood on the dock
    > in the evening and listened, and could hear these strange scratching
    > sounds, as if there were thousands of little tiny organisms nibbling on
    > the docks or hull of the boat.  We could not see anything in the water
    > that was unusual.
    >
    > Has anyone ever heard anything like this before on their boats?  Does
    > anyone have an explanation for this?
    >
    
    
    

       
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