The reliability of skinfold-calipers for measuring blubber thickness of Steller sea lion pups (Eumetopias jubatus).

Twelve dead Steller sea lion pups (Eumetopias jubatus) aged 3-14 d were rec overed from rookeries in Southeast Alaska. They had a wide range of body si zes and conditions (small to large and fat to no fat). The ability of calip ers to estimate the thickness of their blubber layer was assessed with a se t of skinfold calipers. Average error of measurement for skin and blubber t hickness was an acceptable 5.4%, but the skin and blubber of the pups were highly compressible. Skinfold thickness increased with body mass but did no t necessarily reflect the development of blubber, given that pups with no b lubber also showed an increase in skinfold thickness with increases in body mass. Skinfold thickness of sea lion pups appears to predict body site bet ter than it predicts blubber thickness, making it difficult if not impossib le to develop a simple index of body condition or a calculation of percent body far for Steller sea lion pups from skinfold caliper measurements.