Effects of food deprivation on blood lipid concentration and composition in Steller sea lions (Eumetopias jubatus)

Steller sea lions fast 12-43 days during their breeding season. This study determined utilization of lipids and mobilization fatty acids during fasting. Plasma non-esterified fatty acid (NEFA) concentrations were analyzed spectrophotometrically. Serum fatty acid (FA) composition was analyzed using gas chromatography resulting in FA weight percents (wt%). Juvenile NEFA concentrations ranged from 1.2 +/- 0.51 mM to 3.7 +/- 0.69 during fasting. Sub-adult NEFA concentrations ranged from 1.00 mM to 9.70 mM. The wt% of one FA was significantly different between breeding (BS) and non-breeding seasons (NBS) in juveniles. Seven FA changed significantly in the juveniles and five were significant in separating the beginning and end of fasting using principal components analysis (PCA). The wt% of 10 fatty acids were significantly different during BS and NBS in sub-adults. Ten FA changed significantly in sub-adults; four were significant in separating the beginning and end of fasting using PCA. Trends reveal physiological differences between the juvenile and sub-adult Stellers and suggest that sub-adults are better adapted to fast.