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At-sea distribution of female southern elephant seals relative to variation in ocean surface properties

Bradshaw, Corey J. A., Higgins, J., Michael, K. J., Wotherspoon, S. J. and Hindell, Mark A. (2004). At-sea distribution of female southern elephant seals relative to variation in ocean surface properties. ICES Journal of Marine Science,61(6):1014-1027.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 39 times in Scopus Article | Citations

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Title At-sea distribution of female southern elephant seals relative to variation in ocean surface properties
Author Bradshaw, Corey J. A.
Higgins, J.
Michael, K. J.
Wotherspoon, S. J.
Hindell, Mark A.
Journal Name ICES Journal of Marine Science
Publication Date 2004
Volume Number 61
Issue Number 6
ISSN 1054-3139   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-4644251219
Start Page 1014
End Page 1027
Total Pages 14
Place of Publication United Kingdom
Publisher Elsevier
HERDC Category C1 - Journal Article (DEST)
Abstract We examined the relationships between physical oceanography (sea surface temperature SST, sea surface height anomaly - SSH, ocean colour - OC, bathymetry - BA, sea-ice concentration - SI, and their associated gradients) and the foraging distribution (time at sea) of female southern elephant seals using generalized linear and generalized additive models (GLM and GAM). Using data from 28 separate foraging trips (22 unique individuals) over two years, we found that during the post-lactation trips (summer), the best GLM demonstrated a negative relationship between time at sea and SST and BA, but a positive relationship with SST gradient and SSH. During the post-moult (winter) trips, there was a negative relationship with OC gradient, SSH, and BA. The best post-lactation GAM identified a positive relationship with OC gradient, negative relationships with CC and SST gradient, and a non-linear relationship with SST. For the post-moult trip there was a negative relationship with OC, SST, BA and BA gradient, and a positive relationship with SST gradient. The relationship between the predicted time and observed time at sea was significant only for the post-lactation GAM, although predictability was low. That SST and its gradient predicted a small, but significant proportion of the variation in time at sea is indicative of the frontal zones within this area that are generally more biologically productive than surrounding regions. It appears that coarse-scale oceanographic configuration influences foraging behaviour in southern elephant seals only subtly. Nonetheless, some of the mechanisms influencing predator foraging are congruent with expectations of distribution of marine food resources at coarse spatial scales. (C) 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
Keywords bathymetry
elephant seals
environmental variation
generalized additive model
generalized linear model
sea surface temperature
antarctic fur seals
sperm whale distribution
oceanographic features
foraging ecology
king penguins
macquarie island
polar front
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