Subject: Echolocation etc.

Kim Marshall (kim@Whale.Org)
Thu, 20 Feb 1997 16:37:26 -0500 (EST)

To the class at Norman & Carolina Martijnse,

? ... Has there been any research about the possibility that the human
changes to the environment is the reason for more beaching of whales.?
Yes, indirectly.  There is work on the levels of toxins/chemical pollutants
that are bioaccumulating in marine mammals.  This type of poisoning causes
the whales/dolphins to have weakened immune systems which makes them more
susceptible to illness.  It is believed that one of the reasons they strand
on beaches is because the leader of the pod gets ill.  Other reasons for
beaching are related to the earth's magnetic pull and debris in the water
that reduces their ability to echolocate.  Whales have a mineral in their
heads called magnetite which might confuse their abilities to navigate when
near land masses that can react to this mineral.  It is an ancient
occurance of pilot whales to strand on beaches like that at Wellfleet in
Cape Cod - there is no definate evidence that there is more or less
occurances or that is directly related to changes in the environment.


? ... In connection to our pollution how did we change the way whales find
there way in the water ?  Whales use now freuquency (infrasonic) and high
frequency (ultrasonic) echolocation to navigate through the waters.  WIth
this ability they don't need use their eyes - they can see things in the
water like an xray.  WIth the increasing numbers of ships and boat traffic
we have increased the noise pollution which absorbs the sounds of the
whales.  It is not known for sure if this affects how they find their way
in the water.


? ... Are there maps indicating the change in movement of whales throughout
the decades ?

In general ,whales don't change their migration routes.  They follow
ancient long paths that are memorized and passed down through generations.
I am sure there is some movement but I do not know of any maps showing
this.

Is it possible to read an studypaper, by a marine biologist who can answer
the following questions on the internet and where to find them :
My advise is to keep monitoring the Whale Conservation Institute's webpage
and the Whalenet webpage for new links and papers.


Thank you very much for your well thought out questions!  Kim Marshall