Subject: Whale Age: Reproduction in old whales (fwd)

Mike Williamson (pita@www1.wheelock.edu)
Tue, 12 Aug 1997 17:40:02 -0400 (EDT)

Subject: Reproduction in old whales

** High Priority **

If I am reading the paper correctly, Dale Rice's message concerning age
data on old fin whales, taken from Nishiwaki et al (1958), is misleading.
Dr Rice quotes a figure of 100 laminations for a lactating female and links
this to Ohsumi's estimate that 1 lamination per year is laid down.  This
implies that a 100-year-old female was lactating.

The Nishiwaki paper, however, states the following (page 155):

  "It is considered in our studies that 2 laminations are deposited in one
year in the ear plug."

This is repeated later on in the paper, and echoes current opinion that the
growth rate is one Growth Layer Group (one light, one dark lamina) per
year.

Consequently, all of the figures in this paper (given in the Appendix)
should be divided by two, not one, to get an approximate age of the
animal in question.

Alex Aguilar and Christina Lockyer (1987 in Can J Zool) looked at animals
in the Spanish catch and found fin whales with up to 80 GLG's (i.e. 80
pairs of laminae, implying an age of around 80 years).  If I recall
correctly, Alex also had an animal that was pregnant in her 60's, but to
my knowledge there is no record of a greater age for active reproduction
in baleen whales.

Phil Clapham
Smithsonian Institution
claphamp@nmnh.si.edu