Military sonar exercises have caused mass strandings and deaths of beaked whales and dolphins, representing a significant anthropogenic welfare threat to deep-diving cetaceans.
Military sonar causes acute welfare harm to cetaceans through acoustic trauma and by triggering behavioral responses that lead to decompression-like injuries when whales surface too rapidly to escape the sound source. Animals strand alive on beaches showing signs of severe distress before dying. The mechanism is relatively well understood but military necessity arguments have limited regulatory response. Mitigation measures including marine mammal observers and sonar ramp-up protocols reduce but do not eliminate harm.