Australian Fur Seals Arctocephalus Pusillus Research Articles

Mechanisms for sex-based segregation in foraging behaviour by a polygynous marine carnivore

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 624:213-226 (2019) - DOI: https://doi.org/10.3354/meps13036 Mechanisms for sex-based segregation in foraging behaviour by a polygynous marine carnivore Marcus Salton1,2,3,*, Roger Kirkwood2, David Slip1,4, Robert Harcourt1 1Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia 2Research Department, Phillip Island Nature Parks, Cowes, Victoria 3922, Australia 3Australian Antarctic Division, Department of Energy and Environment, Kingston, Tasmania 7050, Australia 4Taronga Conservation Society Australia, Mosman, New South Wales 2088, Australia *Corresponding author: marcussalton@gmail.com ABSTRACT: Sexual segregation in foraging is often attributed to constraints arising from sexual size dimorphism, such as differing physiological abilities and energy requirements, or to reproductive commitments including nutritional requirements and behavioural limitations such as parental care. In species with sexual size dimorphism and a polygynous mating system, there are sex differences in both body size and reproductive commitments, so distinguishing the mechanism underlying sexually segregated foraging is particularly difficult. We investigated movements of the sexually dimorphic, polygynous Australian fur seal Arctocephalus pusillus doriferus, and compared foraging strategies of juveniles to adults in order to investigate foraging constraints associated with differences in body size separately from those also associated with reproduction. Foraging trip duration, range, core area, and distance to core area from the breeding site were similar between the sexes in juveniles and adults, but juveniles were overall more constrained than adults. After foraging trips, juveniles and adult females were more likely to return to the breeding site than to other sites, probably because of physiological limitations (juveniles) or reproductive commitments (adult females). Freedom from reproductive commitments allowed adult males to reside in areas away from the breeding site and thereby meet the higher energy requirements arising from their larger body size, without competing with adult females. Consequently, intra-species differences in foraging strategies of Australian fur seals are shaped first by foraging constraints associated with body size, and to a lesser extent by reproductive behaviour. KEY WORDS: Intra-species competition · Ontogeny · Allometry · Sex segregation · Foraging · Otariid Full text in pdf format PreviousCite this article as: Salton M, Kirkwood R, Slip D, Harcourt R (2019) Mechanisms for sex-based segregation in foraging behaviour by a polygynous marine carnivore. Mar Ecol Prog Ser 624:213-226. https://doi.org/10.3354/meps13036 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 624. Online publication date: August 15, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Morphometric and molecular characterization of the species of Uncinaria Frölich, 1789 (Nematoda) parasitic in the Australian fur seal Arctocephalus pusillus doriferus (Schreber), with notes on hookworms in three other pinniped hosts

This study presents morphological and molecular data on hookworms from the Australian fur seal Arctocephalus pusillus doriferus (Schreber) currently identified in Australian waters as Uncinaria hamiltoni Baylis, 1933. Additional specimens from the Australian sea lion Neophoca cinerea (Péron) and the New Zealand fur seal Arctocephalus forsteri (Lesson) from Australia, and the Southern elephant seal Mirounga leonina (Linnaeus) from Antarctica, were included. Using the internal transcribed spacer (ITS), hookworms from A. p. doriferus, N. cinerea and A. forsteri were found to be genetically similar but distinct from Uncinaria spp. found in M. leonina from Antarctica, as well as from Zalophus californianus (Lesson) and Callorhinus ursinus (Linnaeus) from California. Few morphological differences were detected between these taxa.

Genetic status of an endemic marine mammal, the Australian fur seal, following historical harvesting

Genetic variation, and the way in which it is partitioned among populations, has implications for a species' survival and evolutionary potential. Such information is particularly important for the successful conservation and management of species that have experienced past human impacts and potential losses of genetic diversity. Overharvesting of the Australian fur seal Arctocephalus pusillus doriferus in the 18th and 19th centuries resulted in severe population reductions and elimination of an estimated 17 of 26 colonies. Currently, the subspecies is recovering and c. 20 000 pups are produced annually at 13 colony sites, most of which are situated in Bass Strait in south-eastern Australia. Genetic analysis of samples collected from pups captured at nine colonies revealed no difference in allelic diversity or heterozygosity at five microsatellite loci and no differences in haplotype diversity within a 344 bp region of the mitochondrial DNA control region. There was some evidence for isolation by distance but the program structure predicted a single cluster of individuals. Gene flow among colonies appears to be substantial at present, indicating that the Australian fur seal is currently a single, panmictic unit.

Milk consumption, body composition and pre‐weaning growth rates of Australian fur seal (Arctocephalus pusillus doriferus) pups

AbstractPre‐weaning growth rates, body composition, milk consumption and mass gain efficiency were measured in Australian fur seal Arctocephalus pusillus doriferus pups born in two consecutive breeding periods. Australian fur seals have the highest birth mass of any fur seal species (male 8.3 kg; female 7.2 kg). While their absolute pre‐weaning growth rate (male 62 g·day−1; female 53 g·day−1) is similar to that of other temperate latitude fur seals, they have the longest birth‐mass doubling time of any otariid species (134–136 days). Daily milk consumption increased from 400 g·day−1 (5 MJ·day−1) after birth to 675 g·day−1 (13.7 MJ·day−1) at age 210 day. However, mean mass‐specific milk consumption (41 g·kg−1) is substantially lower than in other otariid species (58–70 g·kg−1) and, combined with a low mass gain efficiency (0.12 g·g−1), contributes to the low mass‐specific growth rates observed. There were no significant differences in either absolute or mass‐specific milk consumption between the sexes. Significant differences, however, were found between the sexes in the body composition of pups with females generally having larger body lipid stores than males for any given mass. Peak milk yield by Australian fur seal females is estimated at 0.60 MJkg−0.75, substantially less than in Antarctic fur seals. The low level of maternal energy transfer in Australian fur seals may reflect the relatively low marine productivity of their foraging areas.

Pup production and breeding areas of Australian fur seals Arctocephalus pusillus doriferus at Kanowna Island and The Skerries in north eastern Bass Strait.

THE breeding distribution of the Australian fur seal (Arctocephalus pusillus doriferus) is restricted to offshore islands in Bass Strait, southeastern Australia (Warneke and Shaughnessy 1985). Breeding colonies are currently established on only nine islands but there is historical evidence to suggest that several other islands within Bass Strait once accommodated breeding sites (Warneke 1982). Prior to the largescale commercial hunting (1798-1825), the annual total A. p. doriferus pup production is estimated to have been between 20,000 ? 50,000 but these numbers were severely reduced as a result of overexploitation (Warneke and Shaughnessy 1985).

Mercury concentrations in the Australian fur seal Arctocephalus pusillus from SE Australian waters : Bacher, G.J., 1985. Bull. environ. Contamin. Toxicol., 35(4):490–495. Arthur Rylah Inst. for Environ. Res., Fish. and Wildlife Serv., P.O. Box 137, Heidelberg, Vict. 3084, Australia

Mercury concentrations in the Australian fur seal Arctocephalus pusillus from SE Australian waters : Bacher, G.J., 1985. Bull. environ. Contamin. Toxicol., 35(4):490–495. Arthur Rylah Inst. for Environ. Res., Fish. and Wildlife Serv., P.O. Box 137, Heidelberg, Vict. 3084, Australia

Mercury concentrations in the Australian fur seal Arctocephalus pusillus from SE Australian waters.

Marine carnivores such as seals and sea lions occupy an important position in the upper trophic level of the marine food web and this, together with their longevity, makes these marine mammals useful indicators of mercury accumulation in the marine environment. Little information exists on mercury concentrations in marine mammals from the southern hemisphere. This paper reports total mercury concentrations in the tissues of the Australian Fur Seal Arctocephalus pusillus from southeastern Australian waters.