The welfare of killer whales (orcas) in captivity has become a defining issue in public debate about marine mammal parks, with scientific evidence and public sentiment strongly opposing captivity.
Captive killer whales cannot fulfil their fundamental needs for space, complex social groups, and prey hunting. Social disruption from mixing incompatible individuals from different ecotypes causes chronic stress and aggression. Separation of calves from mothers mirrors wild orca social trauma and causes visible distress. The evidence for poor psychological and physical welfare in captive orcas is extensive and has driven major policy changes by leading marine parks.