Preliminary information on temporal changes in the blood chemistry of farmed southern bluefin tuna, Thunnus maccoyii (Castelnau), after feeding and repeated sampling disturbance.
This study was conducted to examine the whether, following feeding, the blood chemistry parameters of tuna would be affected by repeated sampling of fish from the same pen. Five fish were removed from the pen prior to feeding in the morning and further groups of 5 were removed at 2, 4, 8, 12, and 24 h after the morning feed. Plasma cortisol, pH, and insulin-like growth factor (IGF) concentration were determined from blood samples. No significant differences in plasma cortisol, IGF, and pH were observed between sampling times. Fish sampled 2 h after feeding had slightly higher plasma lactate levels than those sampled prior to feeding or 12 and 24 h after feeding. Using the capture method described in this experiment, repeated sampling of tuna from the same pen does not result in fish stress that can be detected by changes in the blood chemistry parameters tested.