Evaluation of transportation procedures on water quality and fry performance in red porgy ( Pagrus pagrus) fry

The effect of stocking density (10, 20, 30, 40 kg/m 3), water renewal (0% or 100% renewal rate per hour), hauling temperature (14, 19, 24 °C), salinity (20, 25, 30, 35, 40 psu), and use of anaesthesia (0, 10, 20, or 50 ppm ethynelglycol-monophenylether) prior to transportation on red porgy's fry performance, liver glycogen, and water quality parameters was tested to evaluate transportation procedures in a promising candidate for aquaculture. Simulated transport was performed in plastic containers (volume 60 l) for 48 h. Water samples were taken at 4-h intervals after transport for the determination of pH, carbon dioxide (CO 2), un-ionised ammonia (NH 3) and ammonium (NH 4 +). Additionally, liver samples were collected at 4 and 48 h for glycogen determination. There were no statistically significant fluctuations in dissolved CO 2 concentration in all tested conditions. Stocking density did not affect NH 3 and NH 4 + average values and hepatic glycogen content in groups exposed to a water renewal rate of 100%, while increasing NH 3 and NH 4 + average values with increasing stocking density was observed in groups with no water renewal. Under the same stocking density, a significant change in NH 3 and NH 4 + fluctuations over the duration of the experiment was observed with concentrations increasing, with a mean exponential rate (±SD) of 0.060±0.005 (NH 3) and 0.062±0.005 (NH 4 +) per hour in groups with no water renewal, and −0.033±0.004 (NH 3) and −0.024±0.007 (NH 4 +) per hour in groups with 100% water renewal. Water temperature affected significantly the hepatic glycogen content and survival during transport. There was no significant effect of salinity and anaesthetic (except at a dose of 50 ppm) on fry survival and on the water quality parameters. It is suggested that red porgy should be transported in stocking densities of 20–25 kg/m 3 and at a hauling temperature similar to that kept at the exporter's fish rearing tanks (preferable 19 °C). Besides, it is recommended to avoid temperature differences between the hauling water and the water used for renewal during fry transportation.