Oxygen stores of California sea lion pups: Implications for diving ability

Oxygen stores of California sea lion pups: Implications for diving ability

C.E. Kuhn, D. Aurioles-Gamboa, M.J. Weise, and D.P. Costa

Oxygen stores of California sea lion pups: Implications for diving abilityThis is part of Sea Lions of the World
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Description

Diving mammals are faced with the challenge of locating and catching prey while also breath-holding. The most efficient way to maximize total time under water is to use aerobic metabolism, relying on the oxygen stored in the blood, muscle, and lungs. While oxygen stores have been measured in adult animals, there are few reports on the development of oxygen stores in young pinnipeds as they transition to independence. This study examined the total body oxygen stores of California sea lion pups (Zalophus californianus) at or near weaning in April 2003 at Los Islotes, Mexico (24º35'N, 110º23'W). We measured mass, plasma volume, blood volume, hematocrit, hemoglobin, and muscle myoglobin content. These values were used to estimate total oxygen available to pups in the blood, muscle, and lungs.

Pup mass ranged from 26.4 to 42.4 kg (mean 33.0 ± 4.7 kg). Mean plasma volume was 1.6 ± 0.1 L and total blood volume was 9.9% of mass. Mean hematocrit, hemoglobin, and myoglobin concentration were 52.4 ± 0.9%, 22.9 ± 2.8 g per 100 ml, and 2.3 ± 0.6 g per 100 g muscle, respectively. Based on these values, mass specific oxygen stores were estimated to be 34.5 ± 2.2 ml O2 per kg. At or near weaning, California sea lion pups at Los Islotes have only 53% of adult female oxygen stores and therefore will not be able to forage on the deep prey resources exploited by adults in this population.

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