Fecal glucocorticoid metabolites can be used as a stress indicator in bottlenose dolphins (Tursiops truncatus).

Background: Glucocorticoids increase in response to the hypothalamic-pituitary-adrenal axis stimulation, and their metabolites can be measured in dolphins' feces.

Aim: This study aimed to assess the welfare of bottlenose dolphins under human care by measuring fecal glucocorticoid metabolites (FGM).

Methods: Our study consisted of measuring glucocorticoid metabolites concentration by enzyme immunoassay in fecal samples from five bottlenose dolphins housed in a dolphinarium. Dolphins were sampled once a month over a year, and 1 day before and 2 days after the three stressful events.

Results: We confirmed the validation of an extraction technique and an enzyme immunoassay to measure FGM and we observed an increase in their concentration after the stressful events, which provides a biological validation of this method. In parallel, we confirmed that males had a higher concentration of FGM than females, with a basal concentration of around 80 and 50 ng/g of dried feces, respectively.

Conclusion: Our study confirms that FGM measurement is a relevant indicator of stress response in bottlenose dolphins under human care, although it needs to take into account the sex and reproductive status of the animals.