Seasonal and interannual variability in the diet of young and subadult male Antarctic fur seals as revealed by stable C and N isotope ratios

Detailed knowledge of marine mammal diet is critical to understand their ecological roles and for the adequate management of marine resources. Antarctic fur seals ( Arctocephalus gazella) in the Southern Atlantic Ocean rely largely on Antarctic krill ( Euphausia superba) during the summer months, bu...

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Bibliographic Details
Published in:Canadian journal of fisheries and aquatic sciences 2023-01, Vol.80 (1), p.69-84
Main Authors: Drago, Massimiliano, Llorach, Celia, Santa Cruz, Unai Ormazabal, Zenteno-Devaud, Lisette, Rebolledo, Lorena, Rita, Diego, Gazo, Manel, Cardona, Luis
Format: Article
Language:English
Subjects:
Aquatic mammals
Arctocephalus gazella
Diet
Euphausia superba
Fisheries
Fisheries management
Isotope ratios
Isotopes
Krill
Males
Marine mammals
Marine resources
Marine resources management
Nitrogen isotopes
Plankton
Prey
Seals
Stable isotopes
Vibrissae
Winter
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Summary:Detailed knowledge of marine mammal diet is critical to understand their ecological roles and for the adequate management of marine resources. Antarctic fur seals ( Arctocephalus gazella) in the Southern Atlantic Ocean rely largely on Antarctic krill ( Euphausia superba) during the summer months, but their winter diet remains largely unknown. Here, stable carbon and nitrogen isotope ratios in whiskers and blood of young (2–3 years old) and subadult (4–7 years old) Antarctic fur seal males from the South Shetland Islands were used to assess the seasonal and interannual changes in the krill contribution to their diet. The stable isotope ratios revealed that krill dominated the diet of young and subadult male Antarctic fur seals year-round, with penguins, and not fish, as the second major prey, regardless of year and season. The year-round reliance of young and subadult male Antarctic fur seals on krill should be considered for ecosystem-based fisheries management, as they represent the bulk of the fur seal population remaining off Antarctica during the winter months.
ISSN:0706-652X
1205-7533
DOI:10.1139/cjfas-2022-0145