Uwe Waller

Growth of European sea bass (Dicentrarchus labrax L.) under hypoxic and oscillating oxygen conditions

Effects of moderate hypoxia and oscillating oxygen conditions on growth of European sea bass (Dicentrarchus labrax L.) were investigated. Groups of four to six sea bass (initial weights 40–90 g) were exposed to one of three oxygen regimes (40% air saturation; oscillations between 40–86% with a period of 770 min; 86% as a control) at 22°C and a salinity of 37 for 1 month. All fish survived and gained weight, but relative to the controls, the sea bass exposed to hypoxic conditions consumed significantly less food, exhibited a reduced growth, and had a lower condition factor. Oscillating groups were intermediate, and not statistically distinguishable from either normoxic or hypoxic treatments. Feed conversion efficiency and variation in body size were not significantly affected by oxygen conditions. Growth was correlated with feed intake, suggesting that reduced growth under moderate hypoxic or oscillating oxygen conditions is primarily due to reduced appetite and not a consequence of a decrease in feed conversion efficiency.