Evaluation of different stocking densities in a Senegalese sole (Solea senegalensis) farm: Implications for growth, humoral immune parameters and oxidative status

Abstract Fish are usually exposed to farm operations that can activate the stress system, which in turn diverts energy from normal metabolic processes (i.e. growth or immune defence) to deliver it into the physiological systems activated to cope with stress. The main goal of this study was to assess the effect of high stocking densities on growth performance of Senegalese sole ( Solea senegalensis ) juveniles reared under intensive farming conditions. The impact of high densities on plasma cortisol and metabolites, humoral immune parameters and hepatic oxidative status was evaluated. Senegalese sole juveniles (45 ± 5 g average body weight) were stocked at three different initial densities (7, 17 and 24 kg m − 2 ) throughout a 60 days rearing period. Final stocking densities were 13, 31 and 40 kg m − 2 with no differences in terms of growth performance. Similar levels of plasma cortisol, circulating leucocytes and metabolites and humoral innate immune parameters suggest that stocking densities do not affect the hematological and biochemical status of Senegalese sole juveniles, at least under the current experimental conditions. Overall, this study presents the possibility for Senegalese sole on-growing at high stocking densities, strengthening the needs for its intensive commercial farming.