NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: [navigation] Noisy Sea Surface
From: John Kabel
Date: 2003 Nov 14, 14:18 -0500
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? >