There is little information about the reproduction of sea otters. Most often, marine otters adhere to monogamous behavior, but if otters accumulate in large numbers in places of abundance of food, it is often possible to observe polygamous relations between them.
The marital period for sea otters is in December-January. When pairs are formed and mating occurs, males often fight among themselves. Even mating partners can fight with each other.
Pregnancy lasts 60-70 days. The birth of babies occurs in the den. One female can have 5 puppies, but more often two children appear on the light. The family sometimes changes their refuge.
The mother feeds the cubs with milk for several months. Young sea otters do not leave their parents for 10 months. Parents bring their puppies food and teach them how to hunt. Sexual maturation in sea otters occurs in 2-3 years.