Feed intake, growth rate and body composition of juvenile Baltic salmon exposed to different constant temperatures

Feed intake, specific growth rate and changes in body composition of age 1+ and 2+ Baltic salmon, Salmo salar L, were studied for fish held under constant temperature conditions. The 1+ fish (60 g) were reared for 6 weeks at 11, 15, 17, 19 or 23 degrees C and 2+ fish (250 g) were held at 15 degrees C. Feed intake of 1+ salmon increased from 176 kJ kg(-1) day(-1) at 11 degrees C to 275 kJ kg(-1) day-1 at 17 degrees C and decreased to 229 kJ kg(-1) day(-1) at 23 degrees C. Specific growth rate increased from 1.18% day(-1) at 11 degrees C to 1.59% day(-1) at 15 degrees C and decreased to 0.56% day(-1) at 23 degrees C. Optimum temperatures for feed intake and growth were estimated at 17.8 degrees C and 15.6 degrees C, respectively, and estimated upper thermal limits for feeding and growth were 29.0 degrees C and 24.1 degrees C, respectively. Models for feed intake and growth rate in relation to temperature and fish size are presented. The utilization efficiency of ingested energy decreased from 57% at 11 degrees C to 22% at 23 degrees C. For all groups of if fish, most (approximately 86%) of the weight gain consisted of water. Lipid deposition accounted for about 52% of the body energy gain irrespective of rearing temperature.