The diet of the subantarctic fur seal Arctocephalus tropicalis at Marion Island
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Date
Authors
Makhado, Azwianewi Benedict
Bester, Marthan Nieuwoudt
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Scats of subantarctic fur seals Arctocephalus
tropicalis at Marion Island were collected from 1996 to
2,000, to examine temporal variability in the diet, factors
affecting the variability and how the diet differed from
that of the Antarctic fur seal A. gazella in the same
period. For A. tropicalis, 19 prey species, of which 18
were fish and one a cephalopod, were identified in 213
scats. Fish were the main prey, occurring in 98.1 % of
scats, whereas the cephalopod was present in only 1.4 %
of scats. Amongst fish species, Myctophidae were most
abundant, with Gymnoscopelus piabilis, G. fraseri and
Electrona carlsbergi being the commonest prey items.
Other fish families present in the diet in small numbers
were Channichthyidae, Paralepididae, Nototheniidae, Microstomatidae
and Notosudidae. Fish eaten ranged in size
from Protomyctophum bolini and Krefftichthys anderssoni
of standard length (SL) 25 mm to a single Dissostichus
eleginoides of SL 249 mm. Differences in the diet existed
between summer and winter. However, prey type
accounted for most variability in the diet. In previous
studies based on scats, a dominance of fish in the diet of
A. tropicalis was also found at Possession Island (Iles
Crozet), Amsterdam Island and Macquarie Island, but the dominant prey species differed between the various
localities, also suggesting that prey availability is a major
determinant of diet. At Marion Island, from 1996 to 2000
the diet of A. gazella comprised similar prey to that of A.
tropicalis, but the proportional contribution of prey types
differed in instances.
Description
Keywords
Arctocephalus tropicalis, Arctocephalus gazella, Diet, Prey availability, Scat analyses
Sustainable Development Goals
Citation
Makhado, AB, Bester, MN, Somhlaba, S & Crawford, RJM 2013, 'The diet of the subantarctic fur seal Arctocephalus tropicalis at Marion Island', Polar Biology, vol. 36, no. 11, pp. 1609-1617.