Farmed Salmon Genetics and Welfare: Fast Growth Revisited in Fish

Selective breeding in Atlantic salmon aquaculture has increased growth rates dramatically, with welfare implications that parallel the broiler chicken genetics problem in poultry.

Key Facts

Atlantic salmon in aquaculture have been selectively bred since the 1970s, with cumulative genetic improvement producing fish that grow 15-20% faster per generation
Fast-growing genetic lines show higher rates of some welfare-relevant conditions including spinal deformities, heart problems, and reduced swimming performance compared to slower-growing lines
Spinal deformities (vertebral compression) affect 5-20% of farmed Atlantic salmon in some production systems and can reduce swimming efficiency, cause chronic discomfort, and affect feeding behavior
The salmon heart condition cardiomyopathy syndrome (CMS) is associated with rapid growth and strenuous exercise — particularly relevant in sea cages where fish swim against currents
Welfare-conscious breeding programs now include health and robustness traits alongside growth rate in selection indices — a significant shift from purely productivity-focused selection
The SalmoBreed program and similar initiatives select explicitly for reduced incidence of welfare-compromising conditions including spinal deformity, heart health, and disease resistance
Genetic selection for stress resilience — breeding fish that maintain welfare indicators better under challenging conditions — is an emerging priority in salmon breeding programs

Welfare Considerations

Farmed salmon genetics and welfare presents a parallel to the broiler chicken situation: decades of selection for rapid growth have produced animals whose physiology is compromised relative to welfare-optimal baselines. Unlike broiler chickens where fast-growth genetics cause near-universal musculoskeletal problems, the salmon genetics situation is more nuanced — some welfare problems are elevated in fast-growing lines but the relationship is complex and mediated by management conditions. The positive development is that salmon breeding companies have begun incorporating welfare traits explicitly into selection programs — recognizing that fish that cannot maintain health under production conditions represent both a welfare and commercial failure. Consumer and regulatory pressure for farmed salmon welfare standards can accelerate this genetic reform by creating market incentives for welfare-positive breeding program outcomes.

What You Can Do

Choose farmed salmon from producers with published breeding program information that includes health and welfare trait selection alongside growth
Support aquaculture welfare research that characterizes the welfare consequences of different genetic lines under production conditions
Advocate for aquaculture regulations requiring welfare monitoring that could detect genetics-related health problems at population scale
Engage with major salmon retailers about their supply chain requirements regarding genetic health monitoring in their farmed salmon sources
Support consumer labeling initiatives that would allow farmed salmon welfare to be communicated through supply chain verification rather than generic claims