To pup or not to pup? Using physiology and dive behavior to answer the Weddell Seal's overwinter question

• Main Author: Shero, Michelle R.
• Other Authors: Mellish, Jo-Ann, Burns, Jennifer, Hardy, Sarah, Costa, Daniel, Buck, C. Loren
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2015
• Subjects: Antarctic; Austral; Erebus Bay; Fairbanks; The Antarctic; Weddell; Antarc*; Antarctica; Weddell Seal; Weddell Seals; Alaska
• Online Access: http://hdl.handle.net/11122/6123

Dissertation (Ph.D.) University of Alaska Fairbanks, 2015 Female Weddell seals (Leptonychotes weddellii) haul-out on the fast-ice surrounding the Antarctic continent in October and November each year to give birth to and nurse their pups. Breeding follows directly after weaning (December) and the annual molt begins in January-February. Animals reduce foraging efforts during the lactation and molting periods, but very little is known regarding the influence of this reduced activity on physiological condition. After a period of embryonic diapause, the annual molt coincides with embryo attachment and the start of active gestation. Consequently, female physiological condition at this time may influence reproductive success the following year. Overall female health and the ability to forage successfully throughout the gestation period (austral winter) may impact the likelihood that a pregnancy is brought to term. Therefore, this study tested whether overwinter changes in Weddell seal physiology and foraging efforts are reflected in reproductive outcomes the following year (i.e., to answer the over winter question of "to pup or not to pup?"). From 2010-2012, 100 (January-February: n = 53; October-November: n = 47) adult female Weddell seals were captured in Erebus Bay, Antarctica to assess overwinter changes in physiological condition and/or dive behavior that may be associated with reproductive success. Morphometric measurements and isotopic dilution procedures revealed that female Weddell seals gain ~10-15% of their body mass across the winter period, primarily in the form of blubber and lipid mass. The proportion of mass and lipid gain was similar regardless of whether females returned the following year and successfully gave birth, or did not produce a pup. Further, the amount of mass and energy acquired across gestation in the Weddell seal was markedly less than previously reported for other phocid species. Despite changes in activity patterns and body composition, Weddell seals maintained blood hemoglobin and ...