Physiological effects of simulated high-density transport of Atlantic cod ( Gadus morhua)

Abstract

Atlantic cod ( Gadus morhua), 0.8–2.5 kg, previously acclimated to full-strength seawater at 8°C, were kept at a density of 540 kg·m −3 water (260 kg·m −3 volume) for 24 h, and thereafter at 1050 kg·m −3 water (540 kg·m −3 volume) for a further 24 h. Mortality and degree of iono-osmoregulatory disturbance were negligible. Simulated transport caused a general stress response, as indicated by an increase in plasma cortisol and glucose levels. No differences were recorded between the fish sampled after 24 h and after 48 h. Oxygen consumption during the first 24 h of simulated transport was the same as that recorded some days later for fish kept at a lower density. There were no differences in muscle and liver glycogen content, or in muscle lactate content of the different groups. The metabolic effects of simulated transport therefore appeared to be moderate. The results indicate that cod can be transported at very high densities provided they receive sufficient supplies of oxygen.