Postma, MartinBester, Marthan NieuwoudtDe Bruyn, P.J. Nico2014-05-212014-05-212013-05Postma, M, Bester, MN & De Bruyn, PJN 2013, 'Age-related reproductive variation in a wild marine mammal population', Polar Biology, vol. 36, no. 3, pp. 719-729.0722-4060 (print)1432-2056 (online)10.1007/s00300-013-1298-4http://hdl.handle.net/2263/39828Life history theory predicts a change in reproduction success with age as energy resources are limited and must be allocated effectively to maximise reproduction and survival. In this study we use three reproductive performance measures; maternal expenditure, offspring weaning mass and first year survival to investigate the role maternal age plays in successful reproduction. Long-term uninterrupted life history data available for Marion Island’s southern elephant seals and mass change estimates from photogrammetry data allow for assessment of age related reproduction performance and trade-offs. Known-aged adult females were photographed for photogrammetric mass estimation (n=29) and their pups weighed at weaning during the 2009 breeding season. Maternal age and proportional mass loss positively influenced pup weaning mass. In turn first year pup return rates (as a proxy for survival) were assessed through the intensive mark-recapture program. Pup survival increased with female age and weaning mass. Pups of young females aged 3 to 6 years have a lower 1st year survival probability compared to pups of older and larger females.en© Springer-Verlag Berlin Heidelberg 2013. The original publication is available at : http://link.springer.com/journal/300Southern elephant sealsMirounga leoninaPhotogrammetryAge-specific reproductionPup survivalLife history theoryPostprint Article