THE STRESS-RESPONSE AND THE PLASMA DISAPPEARANCE OF CORTICOSTEROID AND GLUCOSE IN A MARINE TELEOST, THE SEA RAVEN

The objective of the study was to examine the physiological response to stress in a marine species with a sluggish life-style. The sea raven (Hemitripterus americanus), a marine benthic predator, did not produce elevated catecholamine levels when handled for blood removal, which facilitated repeated blood sampling from the same fish without cannulation. However, this species did release catecholamines in response to an acute stress (1 min of air exposure followed by 1 min of chasing), suggesting a high threshold (degree of external stimulation) for catecholamine release in this species. Plasma cortisol concentration increased significantly only after 1 h and remained elevated 4 h post-stress, showing a delayed response compared with salmonids. Plasma glucose concentration increased significantly at 0.5 h post-stress and remained elevated even at 24 h, while lactate levels dropped between 4 and 24 h post-stress. The delayed cortisol increase may not be due to altered plasma clearance, as no change in the plasma disappearance or tissue uptake of cortisol-derived radioactivity occurred with confinement stress in this species. Also, confinement stress did not alter the plasma disappearance or tissue uptake of radioactivity derived from glucose, indicating a higher production of glucose during stress. Food deprivation significantly increased the plasma disappearance and tissue uptake of both cortisol- and glucose-derived radioactivity in the sea raven. These results indicate that the hormonal response to stress in the sea raven is different from that of salmonids. This altered response may be an adaptation to prevent excess energy mobilization in a species with an inactive life-style and low metabolic activity.