Coho salmon are raised in net-pen aquaculture systems that present distinct welfare challenges around crowding, sea lice, and slaughter.
Coho salmon welfare in net-pen aquaculture is compromised at multiple points. High stocking densities promote aggression and reduce individual fish ability to avoid conspecifics. Sea lice infestations cause chronic pain and physiological stress. Treatment with chemicals or mechanical methods adds additional acute stress. Water quality parameters — oxygen, temperature, ammonia — can deteriorate in net pens during warm periods, causing respiratory distress. Crowding before harvest and slaughter handling are acute welfare challenges. The scientific evidence that salmon are sentient beings capable of suffering makes these welfare concerns morally significant. Progress in certification schemes is slowly raising standards.