Subject: Data seal Report 11/4/98 "Bristol" (fwd)

mike williamson (
Wed, 4 Nov 1998 19:04:37 -0500 (EST)

Subject: seal data "Bristol"

Mike et al,

I just got done looking at what we have from the tag so far, so this is the
story so far (as of today).  After spending a little more than a week
swimming in shallow water and marshes along the south coast of the Cape
(between Chatham and Osterville), #19 has moved east and through the gap
between South Beach and Monomoy Island and now is on the ocean side of
Monomoy.  Monomoy is the area where the largest groups of harbor seals
gather during the winter.  Two days ago she had swum up the Bass River in
Yarmouth,  and spent much of the day there. 

 So far we have gotten thirteen location messages in as many days.  We have
also received one hundred "data messages" that give information about her
diving behavior (so far we have data on nearly 4,500 dives).  This is
actually less signals and data than we were expecting, although we seem to
be doing better as she moves into open water and begins to do more diving.
The data we have received tells us that the tag is not signalling very
often.  This is most likely due to the position the seal has been keeping
in the water.  When the seal is stationary or moving slowly with he head
up, the tag will be under water and will not signal.  The low signalling
rate says this is most likely what is going on.  The good news is that the
low rate of signalling will conserve battery life in the tag and means the
tag will run for more days at this rate.  

So far her dives have been quite shallow.  Her deepest dives have been to
about forty feet and roughly 95% of her dives have been between 6-12 feet
deep.  She has spent roughly 70% of her time between the surface and 6 feet
deep (a little more than 20% of her time between 6-12 feet).  Most of her
deeper dives have come in the last day, now that she appears to be getting
into deeper water.  This much shallow diving is probably not a great thing
in the long run, but may just be "Bristol" getting used to the new
surroundings (spending a lot of time gawking).  The next few weeks should,
hopefully show more deep diving and consistent diving to a depth where she
might be looking for food.  A good sign, though, is that while her dives
have been shallow some of them have been quite long (some as long as 15
minutes or more).  Although  roughly 50% of her dives have been one minute
or less in length almost 30% have been between 1-2 minutes long and about
15% have been between 2-3 minutes long.  The next few days should be
interesting, as we see if she remains near Monomoy or continues to move.



Greg Early
Edgerton Research Laboratory				
New England Aquarium
Central Wharf
Boston, Mass 02110
617-973-5246 (phone)
617-723-6207 (FAX)