Effect of activity level on apparent heat increment in Atlantic cod, Gadus morhua

Exercise causes an increase in apparent heat increment in 50-55 cm Atlantic cod, Gadus morhua. The duration of apparent heat increment required approximately 51, 83, and 101 h for cod fed a ration equivalent to 2.5% body weight (8 degrees C) and forced to swim at 20, 30, and 40 cm . s(-1) in a Brett-type respirometer. The level of peak apparent heat increment increased by approximately 50, 87, and 116% above routine oxygen consumption rate for fed cod swimming at 20, 30, and 40 cm . s(-)1 respectively. The corresponding magnitudes of apparent heat increment increased from approximately 944 to 1910 and 3149 mg oxygen . kg(-1) at 20, 30, and 40 cm . s(-1). These values of oxygen consumption correspond to 8, 16, and 24% of energy ingested over the respective swimming speeds.