Decades of photo-identification in the north-east Pacific have followed individual resident orcas from birth. The records show females giving birth from their teens until roughly their fortieth year, then living on, in some documented cases past eighty, without further calves. Males in the same populations rarely reach fifty.
The pattern is unusual. Genuine menopause, as distinct from occasional old animals that stop breeding, has been established in humans and in five toothed whales: orca, short-finned pilot whale, false killer whale, narwhal and beluga. In orcas the leading explanation is the grandmother effect. Older females lead groups to salmon during lean years, and their sons in particular show reduced survival in the year after a mother dies.
The evidence rests heavily on two well-studied resident populations. Whether transient and offshore ecotypes show the same demography is much less certain, and lifespan claims of a century or more for individual whales have been disputed.