The period immediately before slaughter is one of the highest-stress phases of farmed salmon's lives. Improvements in pre-slaughter handling can significantly reduce suffering in the final hours.
The pre-slaughter phase for farmed salmon involves a cascade of stressors that cause acute suffering. Food withdrawal combined with crowding during the final days creates conditions of intense competition and physical damage. Transfer to well boats involves pumping fish through pipes, sudden pressure changes, and exposure to new environments. The fear response to crowding is measurable through cortisol, glucose and osmolality changes. Inadequate electrical stunning may cause immobility without unconsciousness - a particular welfare risk if the stun does not cover all fish efficiently. The industry has made genuine progress in some regions, particularly Norway, where welfare at slaughter is regulated. However, substantial variation exists globally with many processing operations applying minimal welfare standards.