Samantha Hindle Thesis

Samantha Hindle Thesis-14
iv Table of contents Abstract ......................................................................................................................... ii Preface .......................................................................................................................... iii Table of contents ......................................................................................................... iv List of tables ................................................................................................................. x List of figures ............................................................................................................. xiii Lists of abbreviations............................................................................................... xvii Acknowledgements ................................................................................................... xix Dedication .................................................................................................................. xxi Chapter 1: General introduction ................................................................................ 1 1.1 Study species and sites.................................................................................................... 2 1.2 Methodology ................................................................................................................... 8 1.3 Research objectives and hypotheses .............................................................................11 1.4 Thesis outline ................................................................................................................ 13 Chapter 2: Accelerometers can measure total and activity-specific energy expenditure in free-ranging marine mammals only if linked to time-activity budgets ........................................................................................................................

iii Preface I designed the research protocols and conducted the field experiments described in Chapters 3 to 6, and performed all of the data analyses in all of the Chapters.

I also prepared and wrote Chapters 2 to 6 as stand-alone manuscripts for publication.

As a consequence, the declining NFS (unlike the increasing AFS) had to compromise between the rate of energy acquisition and the pup feeding frequency.

Such reductions in energy intake and time allocated to nursing pups can ultimately lower juvenile survival, and may explain the population decline of NFS in Alaska.

Energy expenditure for each foraging trip was measured using the doubly-labeled water method, and energy gained while foraging was determined from 1) diet composition (scat hard-parts and DNA) and blood stable isotope ratios; and 2) numbers of prey capture attempts (from head acceleration).

Maternal investment in pups was determined from pup growth rates or from energy content of milk samples.66 4.1 Summary ....................................................................................................................... 66 4.2 Introduction................................................................................................................... 67 4.3 Material and methods ................................................................................................... 69 4.3.1 Data collection ....................................................................................................... 69 4.3.2 Morphological identification from hard-parts in scats and prey size ....................70 4.3.3 Prey species identification from DNA sequences analyses ...................................I investigated how female foraging strategies during the breeding season impact the foraging efficiencies and reproductive successes of two fur seal species—one declining (NFS–northern fur seals, St.Paul Island, Alaska) and one increasing (AFS–Antarctic fur seals, Kerguelen Island, Southern Ocean).14 2.1 Summary ....................................................................................................................... 14 2.2 Introduction................................................................................................................... 15 2.3 Material and methods ................................................................................................... 17 2.3.1 Data collection ....................................................................................................... 17 2.3.2 Daily energy expenditure – doubly-labeled water method ....................................19 2.3.3 Diving and foraging behaviour parameters ...........................................................20 2.3.4 Time-activity budget .............................................................................................. 21 v 2.3.5 Dynamic body acceleration ...................................................................................23 2.3.6 Statistical analyses ................................................................................................. 24 2.4 Results .......................................................................................................................... 26 2.4.1 Relationship between total energy expenditure and total DBA.............................I also sought to develop new accelerometry-based methods to easily determine fine-scale energy expenditure at sea (Ve DBA and flipper stroke metrics).Twenty lactating females of each species were captured and equipped with biologging tags to record GPS locations, depth and tri-axial acceleration.

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