Subject: Stranding

Jennifer D. Philips (jphilips@soest.hawaii.edu)
Sat, 31 Oct 1998 19:10:00 -1000

>Dear Ms.Philips,
>	What is your opinion of why whales get stranded? Please e-mail  me at
>Dance11087@aol.com 
>                        Thank You
>                        Kellie Hayes
>

Kellie - 

Strandings probably happen for many different reasons, and as you probably
know there are differing opinions on the issue.  But the truth is that
there are actually different kinds of strandings, each probably brought on
by different causes.  The first type involves individual whales and
dolphins washing ashore already dead.  In these cases, the animal would
have been sick or injured and died at sea, and then just floated until the
current carried them in the shore.  There can be no doubt here why the
animal stranded, though often we have to wonder why the animal died in the
first place. 

Second, the individual whale or dolphin could be sick or injured and wash
ashore while still alive.  These cases instill action in people nearby, who
want to help the animal, either by helping it back out to sea or, if its a
smaller dolphin, bringing it in to a rehabilitation facility.  In my
opinion, I don't think there is any doubt about why sick whales and
dolphins strand.  These are air breathing mammals whose instinct might be
to seek shallow secure water, and land when they are sick or injured.  They
become too weak to swim or fight currents which carry them toward the beach.

Finally, there 's the biggest mystery in whale/dolphin strandings:  the
mass stranding.  In this case entire pods of animals wash ashore, most are
alive and healthy as far as can be seen.  This usually happens to certain
species of dolphins and small toothed whales, almost never to the large
baleen whales.   Why does this happen?  The truth is, we don't know for
sure.  It could be that the whole pod is following one sick animal to
shore.  The pod could become lost, off its usuall path and accidentally
come too close to shore, getting  stuck on land.  The whole pod could be
sick, but there is usually no evidence of this when stranded animals are
examined after death.  My opinion goes to the first expanation, that the
whole pod sticks with even a sick individual.  Dolphins and small whales
are very tightly social animals whose entire lives are spent in the pod
structure.  This social cohesion is also seen when dolphins become
encircled by nets.  If an opening in the net is left for the animals to
escape through, the dolphins will not go through unless multiple animals
can swim through together, abreast.  Individuals will not go through alone
and leave the pod behind.  The same could be happening when whole pods
strand.  

But, then, that's just one possible explanation.  Its an amazing,
frustrating phenomenon, one that we humans can only hope we are not somehow
causing.

Hope this answers your question.  Write again anytime.

Aloha - 
Jen Philips
__________________________________

Jennifer D. Philips		
jphilips@soest.hawaii.edu

Marine Mammal Research Program
HIMB, University of Hawaii at Manoa
PO Box 1106			
Kailua, HI  96734
voice:  (808) 247-5063
fax: (808) 247-5831
__________________________________