Subject: humpback whales (longevity)

Robert Kenney (rkenney@gsosun1.gso.uri.edu)
Thu, 10 Dec 1998 17:46:11 -0500

At 16:20 12/9/98 -0600, you wrote:
>Hi.  I'm a student at Papillion-LaVista HIgh School in Nebraska and I'm
doing a project in my Biology class about Humpback Whales.  I was searching
the net and I ran across a page full of whale facts and things like that and
it said if you had any questions to send you an e-mail.  So, I was wondering
if you could tell me the life span of a Humpback Whale.  I looked all over
for this and I can't seem to find it anywhere.  

That sounds like a very simple question, but it actually is not.  It turns
out that it's very difficult to tell how old a baleen whale is.  With a
toothed whale, you can just take one tooth and saw a slice out of it.  Under
a special microscope you can see lines that are laid down each year, and
count them.  Baleen whales have no teeth, so that doesn't work.  And they
grow very fast, so a 4-year-old humpback and a 40-year-old humpback are
about the same size.  Their ear canal doesn't have a real opening to the
outside, so the wax builds up for their entire lives (it's also hard to find
a Q-tip that big!), forming a plug that has layers in it.  But getting the
plug out requires killing the whale first, it has to be removed right away
(so dead whales which wash up on a beach aren't useful), and it's difficult
to do right.

Another way is to keep track of the same whales for their entire lives.
That way you know how old each one is when it dies.  Of course that means
research projects that last as least as long as the whales live, and we
aren't there yet.  I work with a lot of other scientists on northern right
whales (you can find out a lot more about them on Whalenet).  We can take
pictures of them and recognize individuals.  Right now we know 388 different
ones, and some of them we know from the year they were born.  If you wait
long enough, we'll be able to tell you what the average and maximum life
span is.  But we already have a clue, because a mother right whale that had
her photo in a newspaper in 1935 was photographed again in 1959, 1980, 1985,
1992, and 1995.  Since she had a baby with her in 1935, she was probably at
least ten years old then, which makes her at least 70 in 1995.
Unfortunately, the last time she was seen in 1995 she had a huge wound,
probably from being run over by a ship, so it's most likely that she died.
But we now know that right whales can live at least 70 years.

The closest relatives of right whales are bowhead whales.  In the last few
years Eskimo whalers in Alaska have killed a couple of very large male
bowheads.  When they were cutting up the whales (the entire village shares
all of the meat from the whale), they found the points from old harpoons
(sometimes the whale escapes after being harpooned, and the harpoon head can
stay in them for years).  These particular harpoon heads were very
interesting, because they were made of stone, not steel, and the Eskimos in
Alaska haven't used stone points since the last century.  So those big males
were probably over 100 years old.  And there is one recent study that
suggests bowheads might live past 200.  

Cheers,
Dr. Bob

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 | Robert D. Kenney, Ph.D.                       rkenney@gso.uri.edu |
 | University of Rhode Island                                        |
 | Graduate School of Oceanography                                   |
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 | Narragansett, RI 02882-1197, U.S.A.          FAX:  (401) 874-6497 |
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