Dear Mr. Garrett -
I am a junior at the University of Idaho and am currently working on a
research paper about the causes of whale strandings. Try as I might, I
have not been able to find recent statistics on the number of whales
that beach themselves annually. I was wondering if you had any access
to this sort of information?
Also, I would like to know if you had any opinions on the current
theories for whale strandings. So far, the one that has been mentioned
most often (in papers and by my professors) is the theory concerning
gently sloping shorelines and how they confuse a whale's sense of
direction. I have also heard theories regarding organochlorine
compounds poisoning the whales, parasites in the middle ear, and a
"stress-theory" in which the whale voluntarily beaches itself in
response to a stress in the marine environment. Have you heard of any
of these, and what do you think of them?
Thank you for your time, and I hope to hear from you soon.
I am not aware of any agency that compiles overall statistics on
strandings. There are many categories of strandings, and of course they
take place worldwide. My suggestion is to contact the New England Aquarium
Stranding Network for that information.
The theory you mention about gently sloping shorelines is certainly a
contributing cause in many instances, such as on Cape Cod, at Blackfish
Creek. There the shoreline at high tide allows the whales to come close to
the mouth of the creek, where the preyfish are in greatest concentration.
As the tide retreats, however, the escape routes become mud flats, and the
whales' echolocation is of little use without a clear channel to swim through.
I don't think organochlorines can be a direct factor in strandings because
those effects take years to accumulate and damage endocrine systems. The
damage done by organochlorines is most severe in newborns of heavily
contaminated mothers, as the contaminants are flushed into the young, where
they disrupt physical growth and the development of reproductive, immune
and neurological systems.
Parasites in the inner ear could be a factor in some instances, though
that would not explain why an entire community of up to a hundred would
strand in a single event. The stress theory could make sense in some cases
as well. There are a variety of explanations that may help explain
particular cases, but there remains the phenomenon of mass strandings, in
which most of the community could swim free but seems to voluntarily join
the stranded individuals. In my opinion, this can only be explained by the
extraordinary social bonding demonstrated by some species.
Tokitae Orca Conservation Foundation
2403 So. North Bluff Rd.
Greenbank WA 98253
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