Submitted August 5, 2003
Returned for revision August 21, 2003
Accepted April 28, 2004
Ovary
Ovarian aging in Two Species of Long-Lived Rockfish,
Sebastes aleutianus and S. alutus
Jan-Peter de Bruin ,
Roger G. Gosden ,
Caleb E. Finch *,
and
Bruce M. Leaman
* To whom correspondence should be addressed. E-mail: cefinch{at}usc.edu.
Abstract
Little is known about the ovary during aging in long-lived
fish with respect to follicular stages and de novo
oogenesis. We examined two species of rockfish,
Sebastes aleutianus (rougheye rockfish) and S.
alutus (Pacific ocean perch). Fish were sampled
offshore of British Columbia, age was estimated by otolith
annuli, and the ovaries were examined histologically. In
S. aleutianus, age up to 80 y did not markedly
alter the frequency distribution of oocytes, follicles, or
their total numbers. Similarly, in a larger sample of
S. alutus, the abundance of oocytes and follicles
showed little age trend up through 77 y. However, fish
older than 50 y lacked the largest and smallest oocyte
size classes (40-60, >80 µm) and the smallest follicle
size class (200-350 µm), which results from the later
seasonal developmental state of these older fish. These
data provide evidence that oogenesis continues at advanced
ages in these two species, in contrast to long-held
assumptions about mammals. These species represent an
iteroparous extreme in the spectrum of life history
strategies and merit investigation to determine the
mechanisms for such extended reproductive lifespan.
Key words:
Ovary •
Aging •
Oocyte development •
Ovulatory cycle •
Seasonal reproduction
