Farmed Salmon Crowding Pre-Harvest: Welfare at End of Life

The final weeks of farmed salmon production involve crowding, feed withdrawal and transport that represent significant welfare challenges. Improving pre-harvest management can substantially reduce end-of-life suffering.

Key Facts

Feed withdrawal before harvest typically lasts 7-14 days to empty the gut and reduce flesh contamination
Crowding fish into pen corners for capture causes acute stress responses measurable in cortisol and behaviour
Atlantic salmon show strong aversion responses to crowding that parallel responses to pain and fear
Pre-slaughter handling including pumping, crowding and transport can last several hours before killing
Water oxygen levels drop rapidly during crowding, causing hypoxia stress
High-welfare alternatives include avoiding feed withdrawal periods longer than 7 days and using two-phase crowding
CCTV and sensor monitoring of oxygen, behaviour and fish density during pre-harvest is increasingly used

Welfare Considerations

Pre-harvest welfare represents one of the largest welfare impacts in salmon farming because it affects every individual at the end of their life. The combination of feed withdrawal-induced hunger, crowding-induced acute stress, hypoxia, and rough handling creates a concentrated welfare burden in the final days. High-welfare operations prioritise minimising crowding duration, maintaining adequate oxygen, using two-phase crowding to reduce aversion, and ensuring effective stunning at slaughter.

What You Can Do

Choose farmed salmon from suppliers with third-party welfare certification covering pre-harvest practices
Ask retailers whether their salmon suppliers have welfare monitoring protocols for crowding and slaughter
Support the Global Salmon Initiative's welfare standards development work
Advocate for mandatory pre-slaughter stunning requirements and maximum crowding duration limits in aquaculture regulation