Males and females only come together during the mating season. Males usually mate with several females that live in or near their own territory.

Mating System: polygynous

Males and females come together to breed in late winter or early spring. Pregnancy lasts two months, but the young may be born up to a year after mating because these otters delay the implantation of the fertilized egg. Births occur from November to May, with a peak in March and April. Females give birth to from 1 to 6 young per litter, with an average of 2 to 3, in a den near the water. They are born with fur, but are otherwise helpless. They open their eyes at one month of age and are weaned at about 3 months old. They begin to leave their mother's home range at from 6 months to a year old. Sexual maturity is reached at 2 to 3 years of age.

Breeding interval: Breeding occurs once yearly.

Breeding season: Mating occurs in late winter and early spring.

Range number of offspring: 1 to 6.

Average number of offspring: 2-3.

Average gestation period: 2 months.

Average weaning age: 3 months.

Range time to independence: 6 to 12 months.

Range age at sexual or reproductive maturity (female): 2 to 3 years.

Range age at sexual or reproductive maturity (male): 2 to 3 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal ); viviparous ; delayed implantation

Average birth mass: 140 g.

Average gestation period: 62 days.

Average number of offspring: 2.5.

Females give birth to, nurse, and care for their young in a den near the water. The young are weaned at about 3 months old and begin to leave their mother at 6 months old.

Parental Investment: altricial ; female parental care