Growth and feeding responses of a hatchery population of brown trout (Salmo trutta L.) at low temperatures

Abstract— Feed intake, specific growth rate and changes in body composition were studied in age 1+ (140-190 g) brown trout ( Salmo trutta L.) reared at three temperatures (2, 4 and 6°C) under continuous light conditions. Feed in take increased from 35.7 kJ-kg⁻¹.day⁻¹ at 2°C to 95.7 kJ-kg⁻¹-day⁻¹ at 6°C, and the growth rate increased from 0.19%-day⁻¹ to 0.42%-day⁻¹ over the same temperature range. The estimated lower temperature limits for feeding and growth were slightly above 0°C. For all groups of fish, the majority (about 75%) of the weight gain comprised water and protein, but lipid deposition tended to increase with increasing temperature. The deposition of lipid accounted for about 50% of the body energy gain at all temperatures.