FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The fourfinger threadfin (Eleutheronema tetradactylum) is an important aquacultural species in the southern coastal district of Taiwan, which is easily subjected to capture and transport stress. Due to the stress caused cortisol increase in fish, therefore, the plasma cortisol levels are used as an indicator to measure the stress of different treatments in E. tetradactylum (15 g ± 2.9 g). The trails were an 1min and 2min period of net handling , and a 60 min transportation at different densities (50 g L-1, 70 g L-1, 90 g L-1); during simulated transportation, the water quality parameters (total ammonia, pH, NH3) were periodic detected during transport . After treatments, fish were moved to the recovery environment and were periodic detected the plasma cortisol levels for 360min duration. The results showed that the treatments of net handling and simulated transportation caused plasma cortisol increase in E. tetradactylum, howerer, the tendencies of recovery were more or less differences. The recovery time of stress in E. tetradactylum after transport trail took more time than handling trail; the recovery time at medium density was much more than that at high and low densities. The total ammonia was accumulated continuously during transport and was proportional to stock densities, which revealed that the high density transportation would deteriorate the water quality. In contrast, the NH3 was inversely proportional to transport densities in term of pH, which showed that the more acidic environment result in better water quality. In conclusion, to maintain good water quality and appropriate recovery time are beneficial to the transport of E. tetradactylum.