Cholesterol levels in the blood of Atlantic salmonids.

Total cholesterol and high density lipids (HDL) were measured in the blood of Atlantic salmon (Salmo salar), brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) from a variety of dietary and environmental regimes. At spawning the total cholesterol of cage reared S. salar was high compared to sea ranched S. salar. Starvation of S. salar in freshwater for 6-11 months depressed total blood cholesterol levels, but not to unusually low levels. A cholesterol supplement of 0.02 g/100 g body weight to a chow diet of 0.38 g/100 g body weight had no significant effect on the total blood cholesterol level in Salvelinus fontinalis. The high proportion of HDL in the blood of S. salar is discussed in terms of its possible importance during the atherosclerotic lesion formation that normally accompanies spawning in these salmon.