Little information is available regarding the mating systems of Commerson's dolphins. They have been observed copulating in a vertical, belly to belly position.
Commerson's dolphins breed between the months of September and February. After a gestation period of at most 12 months, females give birth to one individual in the winter. Calves are born tail first and are grey in color. Newborns range from 0.5 to 0.75 m in length and weigh 4.5 to 7.3 kg. Their dorsal fin and tail flukes are pliable at birth and gradually stiffen as they mature. The length of the nursing period in the wild is unknown. However, in captivity calves begin eating solid food by 2 months of age and take whole fish by 4 months. Males typically reach sexual maturity between 6 and 9 years of age, and females between 5 and 9 years. Individuals from the the south Atlantic Ocean, however, tend to reach sexual maturity at a younger age than populations from Kerguelen.
Breeding interval: Commerson's dolphins breed once yearly.
Breeding season: Mating occurs between late September and early February.
Range number of offspring: 1 (high) .
Range gestation period: 10 to 12 months.
Range birth mass: 4.5 to 7.3 kg.
Range age at sexual or reproductive maturity (female): 5 to 8 years.
Range age at sexual or reproductive maturity (male): 6 to 9 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Average number of offspring: 1.
Mother Commerson's dolphins nurse their calves through abdominal mammary slits for about 9 months. Mothers are attentive to their calves, which swim close to their mother. Calves learn to swim by following in their mother's slip stream. Females also appear defensive of their young.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)