Selective breeding for rapid growth in farmed salmon has produced fish with faster growth rates but also higher rates of deformity, cardiovascular disease, and welfare problems.
The welfare consequences of extreme growth selection in farmed salmon parallel those in broiler chickens — both represent cases where the animal's own body becomes a source of suffering. Salmon bred for rapid growth carry elevated rates of cardiovascular pathology, skeletal deformities that impair swimming, and cataracts that reduce visual acuity essential for predator detection and feeding. These conditions cause chronic discomfort and reduced quality of life throughout the production cycle. Breeding programs that explicitly include welfare traits — disease resistance, normal skeletal development, reduced cataract incidence — alongside growth and feed conversion represent a meaningful welfare improvement that some producers are beginning to implement.