A model to predict fasting capacities and utilization of body energy stores in weaned Steller sea lions (Eumetopias jubatus) during periods of reduced prey availability

    Authors

    D. P. Noren; L. D. Rea;T. R. Loughlin

    Comments

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    Abbreviated Journal Title

    Can. J. Zool.-Rev. Can. Zool.

    Keywords

    NORTHERN ELEPHANT SEALS; METABOLIC-RATE; MIROUNGA-ANGUSTIROSTRIS; CALLORHINUS-URSINUS; FUR-SEAL; FORAGING BEHAVIOR; POSTWEANING FAST; DIVING BEHAVIOR; HEART-RATE; PUPS; Zoology

    Abstract

    The population decline of Steller sea lions (Eumetopias jubatus (Schreber, 1776)) may be linked to a decline in juvenile survivorship. Limitations in prey availability may contribute to the decline, thus it is important to understand fasting capacities of Steller sea lions. For most mammals, fat catabolism is the preferred energetic pathway to ensure that protein is spared. However, marine mammals also have a conflicting requirement to conserve fat because the main site of fat storage is the blubber layer, which is also their primary thermal barrier when at sea. We developed a dynamic state variable model to demonstrate how protein and fat reserve utilization and maximum fasting duration are influenced by body condition and time spent foraging. This model was parameterized with respect to conditions faced by juvenile and subadult Steller sea lions foraging unsuccessfully during a period of reduced prey availability. The model accurately predicted changes in fat and protein mass of juvenile and subadult Steller sea lions fasting in captivity. Furthermore, the model demonstrated that body lipid content, body mass, and the proportion of time spent in water influence energy reserve catabolism and maximum fasting durations. Consequently, small, lean individuals are particularly susceptible to reductions in prey availability.

    Journal Title

    Canadian Journal of Zoology-Revue Canadienne De Zoologie

    Volume

    87

    Issue/Number

    10

    Publication Date

    1-1-2009

    Document Type

    Article

    Language

    English

    First Page

    852

    Last Page

    864

    WOS Identifier

    WOS:000271622500002

    ISSN

    0008-4301

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