life expectancy of gray whales

From: Greg Early (gearly@neaq.org)
Date: Fri Jan 26 2001 - 12:17:52 EST


At 07:35 AM 1/25/01 -0500, you wrote:
>I would like to know how long grey whales live. I can only find general
>information saying that
>whales in general live between 50 and 70 yrs. Can you tell me how grey
>whales live?
>
>thank you
>
>Sylvain de Laplante

Sylvian,

It is no surprise that the best you can find is general estimate, because
that is about all we have for baleen whales.

Aging toothed whales is fairly straightforward. By cutting a thin section
of a tooth, one can see growth layers in the dentine (much like growth
rings of a tree). The only problem then is to figure out if one layer
means one year (or two or more years). This has been worked out for some
species of toothed whales, dolphins and porpoises, so we have a little
better idea about them. Unfortunately, not having teeth, makes aging
baleen whale more difficult. Many methods have been tried, from looking at
wear patterns in baleen, to counting rings of wax collected from their
outer ear canal, but few have proven very reliable. Counting layers in ear
plugs was probably the most commonly used (particularly for whales that
were caught by whalers), so much of what we know is based on those
estimates. Those have given us the general range for most baleen whales of
around seventy to eighty years or so. A couple of flys in the earwax,
however. I am doing this from memory, however, I do not recall how many of
these estimates were done specifically on gray whales, so I am not sure how
reliable the estimate might be. Also, some recent evidence, from bowhead
whales suggests that at least they might live much longer than expected.
Bowheads are still hunted, and several whales that were killed in that hunt
had very old harpoon points still in their muscle. These points were over
one hundred years old, so this opened the possibility that bowheads might
live over two hundred years.

I expect you could find more on this topic by searching the WhaleNet
archives...

ge



This archive was generated by hypermail 2b30 : Mon Feb 25 2002 - 21:05:59 EST