Atlantic and Pacific mackerel are caught in enormous numbers; improving welfare during capture, crowding, and killing is an emerging priority in pelagic fishery management.
The welfare of wild-caught mackerel presents enormous scale challenges. Purse seine fishing aggregates massive schools; crowding during net retrieval causes hypoxia, scale loss, internal hemorrhage, and extreme physiological stress before killing. CO2 narcosis is common but aversive — fish show escape responses before becoming insensible. Chilling in ice slurry slows nervous activity but may not produce rapid insensibility. Percussive stunning followed by gill cutting produces better welfare outcomes but is impractical at commercial scale for small pelagic fish. The welfare case for reducing pelagic fish consumption is strong given the difficulty of improving wild-capture welfare for schooling species.