Rapid growth rates are associated with increased coronary arteriosclerosis in farmed Atlantic Salmon (Salmo salar) under commercial production conditions

Coronary arteriosclerosis, the narrowing and stiffening of the arteries supplying oxygenated blood to the myocardium, is gaining attention as a contributor to stress-related mortality in farmed Atlantic salmon ( Salmo salar ). Rapid growth has been proposed as a risk factor. Thus, clarifying relationships between growth and arteriosclerosis is important, as aquaculture's emphasis on accelerated growth may compromise fish cardiovascular health. Arteriosclerotic lesions were histologically assessed in the main coronary artery of Atlantic salmon at four commercial sites in the Faroe Islands. Fish were sampled after sea transfer and before slaughter to evaluate the effects of hatchery and marine growth. Lesion prevalence (% fish affected), incidence (% artery affected), severity (mean histopathological grade, 0–5), and coronary lumen area reduction for the most severe lesions were assessed. After sea transfer, prevalence ranged from 26 to 67%, with incidences of 5–26% across sites. Lesion severity ranged from 0.1 to 0.3, and lumen area reduction in the most severe lesions ranged from 4 to 14%. Before slaughter, prevalence increased to 90–100% and lesion incidence to 69–84%. Lesion severity ranged from 2.5 to 3, and the lumen area reduction ranged from 15 to 17%. Growth rates were significantly associated with variation in lesion status across sites: higher hatchery growth coincided with greater severity at sea transfer, and higher marine growth was associated with increased lesion progression thereafter. These observational findings indicate that higher growth rates are associated with increased coronary arteriosclerosis in Atlantic salmon under commercial production conditions, suggesting a trade-off between rapid production and cardiovascular health.