Captive killer whales have an overall mortality rate of 4.7% per year. Females have a significantly higher (7.0%) rate than males (2.1%). Larger females have a shorter captive life span than the smaller females. The ability to cope with the psychological dislocation caused by capture may be greater in younger females. The captive state may also possibly reduce intrasexual stress normal to wild males. Less stressful capture procedures may possibly increase captive longevity.