^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ J. Michael Williamson Principal Investigator-WhaleNet <http://whale.wheelock.edu> Associate Professor-Science Wheelock College, 200 The Riverway, Boston, MA 02215 voice: 617.734.5200, ext. 256 fax: 617.734.8666, or 617.566.7369 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ---------- Forwarded message ---------- Date: Wed, 30 Apr 1997 08:44:18 -0400 From: Dagmar Fertl <Dagmar_Fertl@mms.gov> Reply-To: Marine Mammals Research and Conservation Discussion <MARMAM@UVVM.UVIC.CA> To: MARMAM@UVVM.UVIC.CA Subject: abstract - population dynamics of fur seals On behalf of a request made by the Marmam editors, I am posting abstracts for the lastest issue of Marine Mammal Science. This is being cross-posted as well to the ECS mailbase. I have included the mailing address of the author to whom inquiries should be directed, please do not send the mail to me. Dagmar.Fertl@mms.gov ******************************************************************** Wickens, P. and A.E. York. 1997. Comparative population dynamics of fur seals. Marine Mammal Science 13(2): 241-292. Marine Biology Research Institute, University of Cape Town, Rondebosch, 7700, Cape Town, South Africa The population sizes, trends, exploitation, and life history parameters for the ten fur seal species and subspecies are summarized. The largest population is that of _Arctocephalus pusillus pusillus_ with approximately two million seals, and the smallest if _A. townsendi_ with approximately 7,000 individuals. Most populations are legally protected, although controlled harvesting may occur. None of the fur seal populations is currently known to be decreasing. Data are presented for parameters related to the survival of pups, juveniles, adults, and territorial males, and to reproduction, including the age of attainment of territorial status, aggregation sizes, age of first parturition, pregnancy rates, sex ratios of young animals, and information on the birth seasons of the different species. Since pinipeds are often of concern in fisheries management, their daily consumption rates are of importance, and consequently data on body masses are summarized and the paucity fo data on consumption rates as a function of body mass noted. A simplified age-structured model is developed, and the results of this model are compared with results from more detailed models based on two published life tables for _Callorhinus ursinus_. This comparison shows that the use of the simplified age-structured model is justified to explore changes in population growth rate. However, the simplified model does show exaggerated age structure effects compared to the more detailed models. This model is used to compare the population dynamics of those species for which sufficient data are available. Areas in which limited, or no, data are available for the different fur seal species are highlighted.