Transport of juvenile flounder Paralichthys orbignyanus (Valenciennes, 1839): effects of prolonged exposure to air
The changes in the physicochemical parameters of the water during the transport of live fish, and the high costs related to this activity, make the study important to improve and develop new transport technologies. The present work studied the possibility of transporting juveniles of Paralichthys orbignyanus sole without water or “dry” in a simulated way, evaluating secondary responses of stress and survival. The fish (26 ± 2 cm; 227 ± 37 g) were fasted for 24 h and then subjected to a reduction in water temperature from 23 ° C to 10 ° C (1 ° C / h), when they were then packaged for transportation: with water (TA) and dry (TS). The transport lasted 10 h and the temperature was maintained at 10 ° C. Blood samples were taken to assess secondary stress responses; in the liver,muscle and gills were evaluated for lipid oxidative damage (TBARS) and total antioxidant capacity against peroxyl radicals (ACAP). Juveniles were sampled at 0 h, 1 h and 24 h after transport. Survival was 100% in both treatments. Only fish from the TS treatment increased blood glucose immediately after transport, while the lactate and hematocrit concentrations did not differ between treatments after transport and during recovery. The osmolality and the concentration of Cl- in TS were higher soon after transport and 1 h after arrival in relation to TA. The K + concentration was lower in TA at the end of transport, while the Na + concentration was reduced in TA over 24 h. After 24 h, there was no difference in any parameter between treatments.The antioxidant competence in the liver showed a transient increase after 1 h of transport in TA, however in both treatments there were no differences in ACAP in 24 h. The gills had occasional oscillations in the ACAP, while the muscle kept the ACAP values unchanged throughout the experiment. However, no oxidative lipid damage was observed in any tissue in both transports. The results indicate that it is possible to transport sole without water for up to 10 h and transport in water at a density of 68 g / L, since there was no mortality. In addition, dry transport can represent a reduction of up to three times in the cost of transporting live fish.