Cortisol, Aldosterone, and Leucocytes in the Stress Response of Bottlenose Dolphins, Tursiops truncatus

The activity associated with capturing, restraining, and removing bottlenose dolphins, Tursiops truncatus, from water stimulates a stress response as reflected by circulating cortisol, aldosterone, and eosinophils. Serum cortisol increased from resting levels of about 30 to 110 nmol/L within 1 h, aldosterone rose from less than 280 pmol/L to up to 1880 pmol/L within 3 h, and circulating eosinophils were depressed to less than 40% of their initial numbers within 7 h after the animals were removed from water (calm-capture). This basic response was not enhanced when the capture procedure was prolonged for 3 h (chase-capture) or when the dolphins were given adrenocorticotropic hormone and was similar to that observed in free-ranging dolphins after they had been held in a net for up to 5 h. Eosinophil numbers appear to be a consistent and practical indicator of stress in dolphins.