The effect of oxygen saturation on growth and metabolism of Arctic charr (salvelinus alpinus)
The availability of O2 in rearing water is one of the most important water quality parameters in aquaculture. Previous studies have indicated that oxygen saturation under 100% (water equilibrated with air) can reduce the growth rate and metabolic rate of a number of species. At severe levels, hypoxia results in mortalities. The present study examined the long-term effects of O2 saturation in water (60, 80, 100, 120 and 140%) on growth, feeding rate, feed utilization and metabolic rate of Arctic charr (Salvelinus alpinus). The growth performance of charr was not affected by O2 saturation between 60-140%. However, feed conversion and O2 consumption increased significantly with increasing O2 saturation levels. Both routine and active metabolic rates (measured as O2 consumption) increased significantly with increased oxygen saturation. The metabolic scope (difference between active and routine metabolic rate) also increased with O2 saturation. The results indicate that the optimum oxygen saturation for Arctic charr aquaculture is no higher than 60% and, thus, lower than for other species tested such as Atlantic salmon, Atlantic cod, Atlantic halibut and spotted wolfish. These findings have important consequences for the optimization of Arctic charr production.