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    Fasting status of Steller sea lion pups

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    Author
    Crawford, Stephanie G.
    Chair
    Coker, Robert
    Committee
    Rea, Lorrie D.
    Breed, Greg
    O'Hara, Todd
    Keyword
    Steller's sea lion
    Diet
    Infancy
    Metadata
    Show full item record
    URI
    http://hdl.handle.net/11122/12913
    Abstract
    Following population declines in species of concern, wildlife managers often seek to identify underlying causes to understand and predict population dynamics for better future management. Often, physiological and/or behavioral metrics are measurable markers of decline, and these are often detectable well before declines are measurable through population surveys. During the 1970's, 80's, and 90's Steller sea lion (SSL; Eumetopias jubatus) populations in the western portion of their breeding range declined by ~85%. Though declines in most regions have since stabilized or exhibited modest recovery, some subpopulations breeding in the Aleutian Islands continue to decline. In contrast, SSL subpopulations in eastern regions of their range have steadily grown since the 1970s. Prior studies on the maternal attendance behaviors of SSL have noted differences in the timing of parturition, the duration of the perinatal period, foraging trip duration of nursing females, and the duration of periods dams spend ashore tending their pups. Variability in these metrics has been associated with year, location, the dam's age and parity, environmental oscillations (i.e. El Niño Southern Oscillation), and pup age over the lactation period. This study utilized prior findings of predictable changes in metabolite concentrations while pups fasted during their mother's foraging trips as a new approach for assessing maternal attendance patterns. The distributions of fasting phase categories, assigned based on the relative concentrations of plasma betahydroxybutyrate and blood urea nitrogen, were compared across 12 subpopulations extending from eastern Russia along the coastal northern Pacific into southeastern Alaska from blood samples of 1528 SSL pups. Fasting phase categories were merged into Short and Long fasting durations to compare pups sparing critical proteins (relying on lipid reserves) to those with plasma profiles indicative of metabolic protein reliance (muscle & organ breakdown), respectively. Notably the subpopulations with the maximal (western Aleutian Islands) and minimal (eastern Aleutian Islands) observed proportions of Long fasting pups were in the same broad Aleutian Island region. Three metapopulations had significantly greater proportions of Long fasting pups: the western and central Aleutian Islands and the southern portion of southeastern Alaska. Due to contrasting population trends among these metapopulations, we suggest that both density-dependent and density-independent factors contributed to extended fasting durations in SSL pups.
    Description
    Thesis (M.S.) University of Alaska Fairbanks, 2021
    Table of Contents
    Chapter 1: General introduction -- 1.1. Maternal attendance metrics -- 1.1a. Parturition timing -- 1.1b. Perinatal period -- 1.1c. Foraging trip duration -- 1.1d. Shore visit duration -- 1.2. Pup fasting -- 1.3. Summary -- 1.4. References. Chapter 2: Fasting status of free-ranging Steller sea lion pups -- Abstract -- 2.1. Introduction -- 2.1a. Background -- 2.1b. Biomarkers of metabolic status -- 2.1c. Distinctions among fasting phases -- 2.1d. Study importance -- 2.2. Methods -- 2.2a. Study area -- 2.2b. Sample collection -- 2.2c. Metabolite assays -- 2.2d. Fasting phase categorization -- 2.2e. Data selection -- 2.2f. Body condition indices -- 2.2g. Data analysis -- 2.3. Results -- 2.3a. Within-phase comparisons -- 2.3b. Binomial model of fasting duration -- 2.4. Discussion -- 2.4a. Potential drivers for extended foraging trip durations -- 2.4b. Alternate interpretation of increased dam foraging effort -- 2.4c. Future directions -- 2.5. Conclusions -- 2.6. Ethics statement -- 2.7. Funding -- 2.8. References. Chapter 3: General conclusions -- 3.1. Study significance -- 3.2. Study contributions -- 3.3. Future research directions -- 3.4. Summary -- 3.5. References -- Appendix assessment of a point-of-care ketometer for sea-lion blood and plasma.
    Date
    2021-12
    Type
    Thesis
    Collections
    Biological Sciences

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