Primary and secondary stress responses to line capture in the blue mao mao

Primary and secondary stress responses were measured in wild Scorpis violaceus subjected to burst swimming from angling. Fish were blood sampled from 20 s to 30 min after hooking. Consequent rises in plasma adrenaline (14–316 nmol l−1), noradrenaline (25–345 nmol l−1), and cortisol (0.4–197 ng ml−1) correlated with time since capture, and plasma lactate (0.1–12.2 mmol l−1) reflected work done during intense exercise. Haemoglobin concentration and haematocrit also increased with exercise, and erythrocyte swelling occurred. Wild S. violaceus demonstrated a spontaneity and intensity of exercise not seen in fish acclimatized to aquarium conditions. By contrast, the stress responses of fish in captivity, despite careful husbandry, differed qualitatively and quantitatively from those in the wild. Cannulated fish had higher resting plasma cortisol concentrations (61.9±9.5 ng ml−1) than did rapidly caught wild fish (