DAO 57:103-108 (2003)  -  doi:10.3354/dao057103

Heart morphology in wild and farmed Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss

Trygve T. Poppe1,*, Renate Johansen2, Gjermund Gunnes1, Brit Tørud3

1Norwegian School of Veterinary Science, Institute of Morphology, Genetics and Aquatic Biology, PO Box 8146 Dep., 0033 Oslo, Norway
2National Veterinary Institute, Fish Health Services, PO Box 8156 Dep., 0033 Oslo, Norway
3Veterinary Service in Aquaculture, 6681 Valsøyfjord, Norway

ABSTRACT: The normal shape of the salmonid ventricle is a triangular pyramid with the apex pointing caudoventrally. A strong positive correlation has been established between this shape and optimum cardiac output and function. Domesticated salmonids appear to have developed a more rounded ventricle with misaligned bulbus arteriosus. Several reports from fish health veterinarians indicate that fish with abnormal heart morphology have a high mortality rate during stress-inducing situations like grading, transportation and bath treatments. The present paper compares and describes the ventricle morphology of wild vs. farmed Atlantic salmon, and wild steelhead (anadromous rainbow trout) vs. farmed rainbow trout. Several parameters were measured to provide numerical measurement of the differences in shape, i.e. height:width ratio and the angle between the longitudinal ventricular axis and the axis of the bulbus arteriosus. We conclude that the hearts of farmed fish are rounder than those in corresponding wild fish, and that the angle between the ventricular axis and the axis of the bulbus arteriosus is more acute in wild fish than in their farmed counterparts. Further studies are necessary to reveal the prevalence, functional significance and possible causes of these abnormal hearts.

KEY WORDS: Heart morphology · Ventricular shape · Salmonids · Bulbus arteriosus · Salmo salar · Oncorhynchus mykiss

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