Sperm whales are the deepest-diving mammals on Earth, with complex matriarchal societies and cultural traditions, facing welfare threats from plastic ingestion, noise, and historical and ongoing hunting.
Sperm whale welfare is compromised by plastic ingestion, which causes gut blockage, false satiety, and starvation in affected individuals. Their cultural complexity means that loss of a matriarch disrupts knowledge transmission across the entire pod, causing long-term welfare costs beyond the individual. Military sonar causes acute acoustic trauma that may trigger mass stranding events. The continued hunting of sperm whales by Japan and Norway causes welfare suffering through harpoon wounds that may not kill immediately, with drowning and blood loss over variable periods.