The crowding, pumping and killing procedures at salmon harvest cause significant acute welfare harm that has received increasing scientific and regulatory attention.
Crowding salmon before harvest causes hypoxia, scale loss and panic responses. Pumping fish through harvest equipment causes physical trauma. CO2 stunning — widely used in the industry — does not render salmon insensible quickly and causes distress before unconsciousness. Percussion stunning and electrical stunning with proper calibration are more humane alternatives now required in some jurisdictions.