Temperature effects on performance of large Atlantic salmon (Salmo salar) held in seawater recirculation aquaculture systems

Climate change and increasing environmental variability mean that Atlantic salmon are increasingly exposed to sub-optimum environmental conditions throughout the global range of their aquaculture. Recirculation aquaculture systems (RAS) is a technology with potential to remove both environmental extremes and variability for some, or all, of the production cycle. The development of commercial seawater RAS is underway but still requires research to improve the technology. In addition, RAS provides an important facility to understand the impact of sub-optimum environmental variables and their interaction with nutrition variables. The use of RAS as an experimental facility is applicable to tropical and temperature aquaculture research. Experiments aimed to examine the effects of elevated temperature on aspects of feeding and nutrition of seawater pre-harvest Atlantic salmon of 1 to 4 kg in weight. For all experiments, Atlantic salmon grown on site for at least 6 months were distributed amongst 12 recirculation aquaculture systems each consisting of a 2500 L circular tank and associated recirculation and environmental control systems. A reference seawater temperature of 15°C was used. Feed intake was calculated each day and fish were measured for wet weight, fork length and external condition. The effect of elevated temperature on the growth performance, protein metabolism, lipid utilization, fatty acid composition and pigmentation of large seawater Atlantic salmon held in RAS technology will be presented and discussed.