Sperm whales are the largest-brained animals on Earth and face welfare harms from ocean noise pollution, entanglement, and ship strikes in their deep-ocean habitats.
Sperm whale welfare involves both direct acute harms from sonar-associated strandings and chronic stressors from ocean noise disrupting their acoustic ecology across vast ranges. Their cognitive complexity — the largest brains on Earth, complex social structures, cultural transmission of diving traditions — implies rich inner lives where acoustic disruption is not merely physical but potentially psychologically disruptive for animals whose entire sensory world is acoustic. Ocean noise pollution from shipping creates a background of chronic acoustic stress across all sperm whale habitat. Meaningful welfare protection requires quiet ocean zones in critical areas and sonar use restrictions.