Energy-Intake of Immature Southern Elephant Seals, Mirounga-Leonina (Carnivora, Phocidae)

Abstract

We report the mass of food and energy consumed by, and growth of, three immature southern elephant seals from 14 months to 3 years old, at Taronga Zoo, Sydney. The seals were fed four species of fish and one squid genus. There was no consistent or seasonal pattern of variation among the different dietary components, and mean figures for fat, protein, water and energy were used in calculations of dietary consumption by the seals. The mean energy density of the food was 8.65 kJ g-1. The growth rate of the three seals was at the high end of the range for wild southern elephant seals. As in natural populations, growth was positive for most months of the year, but negative from November to January, when fasting, haulout and moulting occur in wild elephant seals of similar age. There was no evidence of fluctuations in energy intake as a result of seasonal variation of temperature or other weather effects. The three animals spent 30% of their time active and 70% at rest. This contrasted with the wild population, in which immature animals of similar age spend more than 70% of their time active and less than 30% at rest. The gross energy intake of the cohort of young, growing elephant seals at Macquarie Island was estimated to be of the order of 1570 x 10(6) MJ per year.