Marine mammals are accidentally caught in fishing gear globally, with hundreds of thousands dying annually from entanglement, drowning, and injury — making bycatch one of the most significant sources of marine mammal mortality.
Marine mammals that drown in fishing nets experience a profoundly distressing death. Cetaceans and pinnipeds must breathe air; entanglement in nets prevents surfacing, leading to asphyxiation over minutes to tens of minutes while the animal struggles. The suffering involved in bycatch deaths is substantial both in intensity and in the number of animals affected. Ghost gear — lost or discarded fishing equipment — continues to entangle and kill marine mammals for years. The welfare case for bycatch reduction measures is compelling independent of conservation concerns. Technology exists to substantially reduce bycatch in many fisheries; implementation requires regulatory requirements and enforcement.