Seasonal variations in biochemical composition and energy content of liver, gonad and muscle of mature and immature cod, Gadus morhua (L.) from Balsfjorden, northern Norway

Seasonal energy changes in mature and immature cod of the same size were studied. For most of the year, the variations in energy content in the tissues of both mature and immature cod are similar. In the period from October to January, the fish accumulate energy. From January until spawning in early April there is a fall in the total energy content. The growth of gonads from January until spawning can explain about one-third of the energy decrease in liver and muscle.