Adult males flock to breeding beaches between October and early November in order to claim their territories. Pregant females arrive one month later. Cows come into estrus six to seven days after giving birth and matings take place from mid December to mid January. Most copulations take place on the sandy beach. Copulation ends when the cow bites at the throat of the bull.
All births take place on the beach. Most births produce only one pup. The pup is nursed by its mother for about a year. Females produce their first pup around age four. Males become sexually mature around age five, but they do not mate until they are around eight years of age.
Average birth mass: 7000 g.
Average gestation period: 365 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 2191 days.