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Trade-offs between foraging efficiency and pup feeding rate of lactating northern fur seals in a declining population

du Dot, Tiphaine Jeanniard, Trites, Andrew W, Arnould, John PY, Speakman, John R and Guinet, Christophe 2018, Trade-offs between foraging efficiency and pup feeding rate of lactating northern fur seals in a declining population, Marine ecology progress series, vol. 600, pp. 207-222, doi: 10.3354/meps12638.

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Title Trade-offs between foraging efficiency and pup feeding rate of lactating northern fur seals in a declining population
Author(s) du Dot, Tiphaine Jeanniard
Trites, Andrew W
Arnould, John PYORCID iD for Arnould, John PY orcid.org/0000-0003-1124-9330
Speakman, John R
Guinet, Christophe
Journal name Marine ecology progress series
Volume number 600
Start page 207
End page 222
Total pages 16
Publisher Inter-Research
Place of publication Oldendorf, Germany
Publication date 2018-07-30
ISSN 0171-8630
Keyword(s) foraging efficiency
reproduction success
northern fur seal
pup growth
diet
science & technology
life sciences & biomedicine
physical sciences
ecology
marine & freshwater biology
oceanography
environmental sciences & ecology
Summary Foraging strategies and their resulting efficiency (energy gain to cost ratio) affect animals’ survival and reproductive success and can be linked to population dynamics. However, they have rarely been studied quantitatively in free-ranging animals. We investigated foraging strategies and efficiencies of wild northern fur seals Callorhinus ursinus during their breeding season to understand potential links to the observed population decline in the Bering Sea. We equipped 20 lactating females with biologgers to determine at-sea foraging behaviours. We measured energy expenditure while foraging using the doubly-labelled water method, and energy gained using (1) the types and energy densities of prey consumed, and (2) the number of prey capture attempts (from acceleration data). Our results show that seals employed 2 foraging strategies: one group (40%) fed mostly in oceanic waters on small, high energy-density prey, while the other (60%) stayed over the shallow continental shelf feeding mostly on larger, lower quality fish. Females foraging in oceanic waters captured 3 times more prey, and had double the foraging efficiencies of females that foraged on-shelf in neritic waters. However, neritic seals made comparatively shorter trips, and likely fed their pups ~20 to 25% more frequently. The presence of these strategies which either favor foraging efficiency (energy) or frequency of nursing (time) might be maintained in the population because they have similar net fitness outcomes. However, neither strategy appears to simultaneously maximize time and energy allocated to nursing, with potential impacts on the survival of pups during their first year at sea.
Language eng
DOI 10.3354/meps12638
Field of Research 0602 Ecology
0608 Zoology
Copyright notice ©2018, The authors
Free to Read? Yes
Use Rights Creative Commons Attribution licence
Persistent URL http://hdl.handle.net/10536/DRO/DU:30113325

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Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au.