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Growth and condition in Australian fur seals Arctocephalus pusillus doriferus (Carnivora : Pinnipedia)

journal contribution
posted on 2002-01-01, 00:00 authored by John ArnouldJohn Arnould, R Warneke
Mass and length growth models were determined for male (n = 69) and female (n = 163) Australian fur seals (Arctocephalus pusillus doriferus) collected at a breeding colony on Seal Rocks (38˚31′S, 145˚06′E), Bass Strait, in south-east Australia, between February and November during 1970–72. Growth was best described by the logistic model in males and the von Bertalanffy model in females. Asymptotic mass and length were 229 kg and 221 cm for males, and 85 kg and 163 cm for females. In all, 95% of asymptotic mass and length were attained by 11 years and 11 years, respectively, in males compared with 9 years and 5 years, respectively, in females. Males grew in length faster than females and experienced a growth spurt in mass coinciding with the onset of puberty (4–5 years). The onset of puberty in females occurs when approximately 86% of asymptotic length is attained. The rate of growth and sexual development in Australian fur seals is similar to (if not faster than) that in the conspecific Cape fur seal (A. p. pusillus), which inhabits the nutrient-rich Benguela current. This suggests that the low marine productivity of Bass Strait may not be cause of the slow rate of recovery of the Australian fur seal population following the severe over-exploitation of the commercial sealing era. Sternal blubber depth was positively correlated in adult animals with a body condition index derived from the residuals of the mass–length relationship (males: r2 = 0.38, n = 19, P < 0.001; females: r2 = 0.22, n = 92, P < 0.001), confirming the validity of using such indices on otariids. Sternal blubber depth varied significantly with season in adult animals. In males it was lowest in winter and increased during spring prior to the breeding season (r2 = 0.39, n = 19, P < 0.03) whereas in females it was greatest during winter (r2 = 0.05, n = 122, P< 0.05).

History

Journal

Australian journal of zoology

Volume

50

Issue

1

Pagination

53 - 66

Publisher

Commonwealth Scientific and Industrial Research Organization

Location

Melbourne, Vic.

ISSN

0004-959X

eISSN

1446-5698

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2002, CSIRO