Transportation induced
behavioural and energetic responses of hatchery=reared rainbow trout, oncorhychus
mykiss (Walbaum), as indicated by electromyogram telemetry
K.P. Chandroo*, S.J. Cooke,
R.D. Moccia and R.S. McKinley
University of Guelph,
Guelph, Canada
Transporting live fish in aquaculture is a common procedure that fish are regularly subjected to, yet little is known about the behavioural responses and energetic costs to fish during and after the transportation episode. The purpose of this study was to examine the swimming activity, behavioural responses and oxygen demands of hatchery-reared rainbow trout (mean fork length = 440 ± 45 mm) during a transportation episode. Fish implanted with electromyogram sensing telemetry transmitters (EMGi) were transported in a shipping tank (4 kg m3; fish/water), for 50 minutes by truck, and then allowed to recuperate for 48 hours in resting tanks. EMGi telemetry signals indicated that vigorous, burst-and-glide swimming occurred during transportation. Telemetry recordings also indicated that fish locomotory activity returned to baseline pre-transport levels within the 48 hour period post-transport (p<0.05). Despite the 48 hour resting period, the swimming performance of fish post-transport was impaired (p<0.05). Respirometry measurements of fish taken after transportation indicated that oxygen consumption was elevated as compared to non-transported fish. The rise in oxygen consumption could be attributed to handling procedures and the intense swimming levels observed during the transportation episode. Therefore, the behavioural responses of fish during transportation may contribute to the overall magnitude of "stress" experienced by fish. The results of this study demonstrate the merit of integrating behavioural and physiological measures when assessing the impacts of routine aquacultural procedures on the health and welfare of farmed fish.