SIZE AND SEASONAL EFFECTS ON THE BODY CALORIFIC CONTENT OF NORTH-SEA WHITING (MERLANGIUS-MERLANGUS L, GADIDAE)

The energy content of juvenile whiting from the North Sea was investig ated in order to describe some parameters which are required as a basi s for bioenergetic models. It was found that the energy content of juv enile whiting changes considerably with growth. The relationship betwe en specific energy content and fish weight was E(spec) = 17 861 x W-0. 04402, where E(spec) = specific energy content [J . g dw(-1)] and W = wet weight of fish [g]. From the different parts of the body (i.e. swi mming muscles, liver and carcass) only the liver showed considerable v ariation in its specific energy content with size. Starting at approxi mately 10 kJ . g dw(-1) at about 10 g ww, its specific energy content increased up to about 32 kJ . g dw-l at a weight of approx. 30g ww. Th ereafter it approached asymptotically a maximum value, according to th e function E(l) = 35 249 x (1-e-(0.0603 x W)), (r(2) = 0.74), where E( l) = specific energy content of the liver [J . g dw(-1)], and W = wet weight of the fish [g]. The specific energy content of the swimming mu scles and the carcass remained almost unchanged with growth. The linea r regressions yielded E(m) = 21 978 + 1.42 x W, r(2) = 0.37, p < 0.01) for muscle tissue, and E(c) = 18 393 + 1.36 x W,r(2) = 0.16, p < 0.05 , for the carcass, with F-m and E(c) = specific energy content of the muscle mass and the carcass [J . g dw(-1)], respectively, and W = wet weight of fish [g].