Food and growth relationships of the cod, Gadus morhua L., with special reference to Balsfjorden, north Norway

Rates of food consumption are notoriously difficult to measure under field conditions and indirect methods must be used. Using data for cod collected from three different areas (North Sea, Faroes & Balsfjorden), food consumption was estimated from stomach fullness and rates of gastric evacuation. These estimates were then compared with estimates given by analysis of food-growth relationships. Although estimates were of the same order of magnitude there were differences. These differences were suggested to be largely due to insufficient knowledge relating to feeding rhythms of wild fish and lack of data regarding the'costs of reproduction'. Differences between the annual energy budgets of cod from the three stocks are discussed.