Metabolic and Hormonal Changes During the Molt of Captive Gray Seals (Halichoerus Grypus)
TLDR Gray seals use more energy and have higher hormone levels during their annual fur-shedding period.
The study on six captive gray seals (Halichoerus grypus) found that during the annual molt, the seals experienced increased energy expenditures and significantly elevated resting metabolic rates (RMRs), especially in juveniles (up to 53%) compared to adults (up to 17%). This increase likely reflected the cost of generating a new pelt or maintaining high skin temperature. Additionally, serum total and free thyroxine concentrations were elevated in all seals during the molt, with juveniles also showing elevated serum triiodothyronine concentrations. These hormonal changes occurred only in the last stage of the molt, suggesting their role in sustaining rapid hair growth or maintaining elevated heat production rather than initiating hair growth.
