Like many pinniped species, southern elephant seals (Mirounga leonina) are conducive to long-term population studies using mark–recapture techniques. The twenty-four year longitudinal dataset at sub-Antarctic Marion Island has already provided much insight into elephant seal population dynamics. However, a limitation of the present dataset is that mother/pup relatedness cannot be examined because pups are only tagged after their tagged mothers have abandoned them. We test the usefulness of two different temporary marking techniques (tagging and ‘strapping’), and four different marker types over two consecutive breeding seasons for use on pups with attending marked mothers. We show that strapping is an ineffective way to mark unweaned southern elephant seals. By comparison, ‘Supersmall^®’ Dalton plastic tags allow quick, effective and easy marking of large numbers of pups with known mothers, without excessive marker loss.