Farmed Salmon Pre-Harvest Crowding Welfare Advanced

Pre-harvest crowding of farmed salmon causes significant acute welfare harm and is an area where improved protocols and technology offer meaningful welfare gains.

Key Facts

Salmon are crowded to high densities before harvest to facilitate capture and reduce handling time
Pre-crowding densities can reach 60-80 kg per cubic metre, several times normal rearing densities
Crowded salmon show elevated stress hormones, tissue damage, and increased mortality risk
CO2 anaesthesia before crowding is used in some high-welfare operations to reduce stress
Camera systems for biomass estimation allow harvest to proceed with less pre-crowding
Water quality deteriorates rapidly in crowded pens, causing hypoxia and gill irritation
Welfare audits now include pre-harvest protocol assessment in some certification schemes

Welfare Considerations

Pre-harvest crowding represents a concentrated period of acute welfare harm in an already challenging production system. The good news is that improved technology and protocols can meaningfully reduce this harm. Crowding duration, density, and management quality make a real difference to individual salmon welfare in the final hours of their lives.

What You Can Do

Choose salmon certified under schemes that include pre-harvest welfare protocols in their standards
Ask retailers about the pre-harvest welfare standards of their salmon suppliers
Support research and investment in technology that reduces the need for extreme pre-harvest crowding
Advocate for welfare-conscious pre-harvest protocols to be included in aquaculture regulations
Support the Fish Welfare Initiative and similar organisations working on salmon welfare improvements