Early mortality syndrome and other developmental conditions in farmed salmon reflect the welfare costs of intensive breeding for growth. Understanding these conditions informs welfare assessment of salmon farming.
Production-related diseases in farmed salmon reflect the welfare costs of extreme selective breeding for growth, mirroring the situation in fast-growing broiler chickens. Cardiac conditions cause circulatory failure and death; the dying process is likely distressing. Cataracts may cause significant visual impairment in a species that relies on vision for feeding. Skeletal deformities cause pain and impair normal movement and feeding behavior. These conditions are not random misfortunes but predictable consequences of breeding priorities that select for growth over health. Slower-growing strains with lower disease prevalence exist and are used in some welfare-focused operations, demonstrating that the welfare trade-off is a choice rather than an inevitability.