The method of killing farmed fish has significant welfare implications. Pre-slaughter stunning prevents pain and fear during the killing process for billions of animals annually.
The welfare gap in fish slaughter is one of the largest in food production — billions of sentient animals killed annually using methods that almost certainly cause pain and distress. Fish suffocating in air, panicking in CO2 immersion, or thrashing in ice slurry are experiencing what the physiological evidence indicates is fear and pain. The contrast with terrestrial food animal slaughter, where pre-stunning requirements are standard in developed nations, reflects the legacy of viewing fish as unfeeling commodities rather than sentient animals. Pre-slaughter stunning technology exists and is commercially viable for major farmed species. The welfare case for requiring its use is strong, and certification scheme adoption is beginning to create market pressure for implementation.