Sperm whales form the most complex societies of any non-human animal after great apes, with matrilineal family groups and cultural dialects whose disruption by commercial whaling caused unprecedented social trauma.
Sperm whale welfare during the commercial whaling era involved not just the death of individual whales but the destruction of entire social networks - clan structures built over generations were shattered by the removal of socially central females. Orphaned calves and disrupted social groups are welfare harms beyond individual mortality. Current sperm whale welfare is threatened by underwater noise from shipping and sonar that masks their communication codas, and by entanglement in fishing gear. The cultural complexity of sperm whales - with clan-specific dialects - means that population recovery without social structure recovery is an incomplete welfare outcome.