Farmed Salmon Crowding Stress at Harvest

The crowding, stunning, and killing process at salmon harvest is a critical welfare point that has received increasing scientific and industry attention.

Key Facts

Atlantic salmon are typically harvested at 3-5 kg body weight after 2-3 years at sea
Crowding for harvest significantly elevates stress hormones for hours before slaughter
Common stunning methods include electrical stunning and CO2 narcosis, with variable welfare outcomes
Percussion stunning followed by spiking (ikejime) provides the highest welfare outcome
Crowding mortality represents 1-3% additional losses at harvest beyond other mortality
The EU requires that fish are rendered insensible before slaughter but enforcement varies

Welfare Considerations

The harvest phase concentrates welfare risks at a single point: fish experience crowding stress over extended periods, followed by a stunning and slaughter process that varies enormously in humaneness across operations. Welfare science increasingly demonstrates that fish experience stress and likely pain, making the quality of stunning critical. Innovations including in-water electrical stunning systems that process fish individually represent a step forward, but adoption is limited by cost. Consumer and retailer pressure for high-welfare harvest standards is one of the most direct levers available.

What You Can Do

Choose salmon from farms with published harvest welfare standards and third-party audit
Ask retailers whether their salmon suppliers use individual electrical stunning or percussion methods
Support campaigns for mandatory welfare-assessed salmon harvest requirements
Reduce consumption of salmon from suppliers with no documented harvest welfare protocols
Support research into cost-effective high-welfare harvest methods