Food consumption estimates of Southern Elephant Seal females during their post breeding aquatic phase at South Shetland Islands.

CARLINI A.; DANERI G.; MARQUEZ M.; BORNEMANN H.; PANARELLO H.; CASAUX R,; RAMDOHR S.; PLÖTZ J.

Workshop; The CCAMLR Ecosystem Monitoring and Management Working Group; 2004

Labelled water methodology was used to quantify energy expenditure during lactation andenergy gain during the post-breeding aquatic phase in Southern elephant seal females atStranger Point, King George Island (25 de Mayo). During lactation females spent a mean of6021±1365 Mj, which resulted in a loss of 35% of the initial mass, comprising 63% of initialbody fat and 20% of initial body protein. During the 58±5.4 d post-breeding foraging period,females gained 135±39 Kg, which allowed them to recover an average of 55% of the mass,including 46% of the fat, 71% of the protein and 47% of the energy lost during lactation.Neither the mass nor the energy lost during lactation were related to those gained while atsea. However, protein loss expressed in absolute terms or as a proportion of that present atthe beginning of lactation explained about 50% of the variation in the protein gained duringthe post-breeding phase. This might indicate the presence of a mechanism favouring anincrease in lean tissue during post-breeding.Daily energy requirements for an average sized female during the post-breeding aquaticphase were estimated at 96 Mj. Estimation of prey consumption varies according toassumptions about diet composition. On a basis of 450 females, the total biomass of fish andsquid consumed by the breeding group, assuming a diet composed of 75% cephalopods and25% fish, was estimated at 521 t and 174 t respectively for the period examined.