Atlantic Salmon Welfare During Pre-Slaughter Crowding

Pre-slaughter crowding of Atlantic salmon is one of the highest welfare-risk events in salmon farming, requiring careful management to minimise suffering.

Key Facts

Salmon are crowded in net pens before pump transfer to slaughter vessels
Crowding typically reduces available space to under 10% of normal conditions
Crowding duration can last 30 minutes to several hours
Cortisol, lactate, and glucose all spike dramatically during crowding
Rapid chilling with ice slurry immediately after pump transfer reduces stress recovery time

Welfare Considerations

Pre-slaughter crowding causes acute and intense physiological stress in Atlantic salmon. Fish at extreme density show erratic swimming, surface crowding, and signs of panic. Oxygen depletion in crowded pens occurs rapidly and causes hypoxic stress before slaughter. Injury from collisions and fin damage is common. Welfare-conscious harvest protocols minimise crowding duration, maintain adequate oxygen supplementation, and ensure slaughter occurs as rapidly as possible after transfer to eliminate prolonged pre-slaughter suffering.

What You Can Do

Support salmon welfare standards specifying maximum crowding duration
Advocate for mandatory stunning before slaughter in salmon aquaculture
Back research into non-crowding harvest approaches for caged salmon
Choose salmon certified under welfare standards with pre-slaughter requirements
Encourage Norwegian and Scottish regulatory reform of pre-slaughter welfare