Larval rearing environment influences the physiological adaptation in juvenile Atlantic cod, Gadus morhua

Abstract

Juvenile Atlantic cod, Gadus morhua, that had been fed rotifers as larvae (R group) had significantly lower growth rates (SGR) at high-ambient ammonia (UIA = 115–120 μg l−1) than did juveniles that had been first fed with natural zooplankton (Z group). Overall specific growth rates (SGRs) were 5–11% higher in the Z group at the control ammonia (UIA = 1–2 μg l−1) treatments. An interaction between larval rearing history, oxygen and ammonia levels was found, as SGR decreased with decreasing oxygen levels at high ammonia in the R group, while the SGR in the Z group were less affected by hypoxia. At high-ambient ammonia, the SGRs were 5% (mild hyperoxia, 101–104% O2 in effluent water), 28% (normoxia, 83–88% O2 in effluent water) and 86% (hypoxia, 57–69% O2 in effluent water) higher in the Z group, compared to the R group. The present findings indicate that larval rearing environment could influence the adaptability to environmental changes and growth performance during later juvenile stage in cod. These findings have implications for the optimization of Atlantic cod culture.