http://www.youtube.com/watch?v=AS4OJk8TR30&feature=related

Females nurse pups for approximately 15–18 months until the next pup is born. If however, a pup is not born in consecutive breeding seasons, many females will nurse existing pups for longer. Females forage for up to two days away from pups, and foraging trips increase in frequency gradually during lactation. Shore attendance bouts were about 1.5 days. This pattern continues until pups are weaned (Higgins & Gass 1993).