Evaluation of the recovery time of Sea bass (Dicentrarchus labrax linnaeus, 1758) juveniles from transport and handling stress: Using ammonia nitrogen excretion rates as a stress indicator

Abstract

A time-course study was conducted in order to evaluate the recovery time of juvenile Sea bass (Dicentrarchus labrax) from transport and handling stress. Among metabolite indices, ammonia nitrogen excretion rates were used as stress indicator. The measurements were carried out in water ambience of 13 ± 1°C under natural light conditions (16L/8D photoperiod). Juveniles were transported for about 2 hours in a fish transport tank with oxygen supply. Handling stress was due to netting at the outlet site during stocking fish into the transport tank and netting at the experimental facility while transferring fish from transport tank into experimental tanks. At the end of transportation, ammonia nitrogen excretion rates of sea bass juveniles in the transport tank became about 4 times higher than that in sea water at the outlet facility. Ammonia nitrogen concentrations in fish exposed to transport and handling stress peaked 10 hours after stocking in to the tanks, and then declined to initial values 24 h after stocking. In fish under normal condition and without stress, the postprandial trend of ammonia nitrogen excretion was similar, however, a peak was reached 6 hours after feeding, and then decreased to initial values 24 h after feeding. Based on the duration for recovery of ammonia nitrogen excretion in fish, it is suggested that sea bass juveniles may completely recover from stress caused by transportation and handling, and return to normal feeding conditions in 24 hours after a 2 hour truck transport.