Variation in blubber cortisol as a measure of stress in beluga whales of the Canadian Arctic
Trana, Marci Renée
Exposure to stressors in free-living mammals can be measured via glucocorticoid hormones concentrations. Using adipose from marine mammals (blubber) as a tissue for extracting cortisol provides a means for measuring cortisol concentrations not associated with capture stress. Beluga whale range is limited to the Arctic where climate change is exaggerated. Our objectives were to compare cortisol concentrations among archived blubber samples with varying quality and blubber depth, compare blubber cortisol from beluga whales in a high-stress entrapment event to whales harvested during subsistence hunts, and compare blubber cortisol among beluga whale populations in relation to conservation status, diet, sex, age and year sampled. Blubber samples showing signs of deterioration had lower cortisol concentrations. The deepest blubber contained the highest concentration of cortisol compared to other depths. Blubber cortisol concentrations from entrapped whales were higher than from harvests. Blubber cortisol was higher in the threatened population when compared to healthy populations.