Decades of genetic selection in Atlantic salmon aquaculture have improved growth rates but introduced health problems analogous to those seen in intensively bred terrestrial livestock.
The genetic history of farmed Atlantic salmon parallels that of broiler chickens and dairy cattle — dramatic productivity gains achieved at the cost of health and resilience. Intensive selection for rapid growth has been accompanied by increased frequency of cardiac, skeletal, and sensory disorders that cause significant welfare compromise in affected fish. Cataracts in particular are striking — affecting the majority of some intensively bred strains, they likely impair the visual predator avoidance abilities of fish and potentially cause chronic sensory deprivation. The emergence of health-inclusive selection indices in Norwegian programs demonstrates that genetic progress and welfare are not inherently opposed — breeding for health alongside growth produces fish with better welfare and often comparable productivity.