The feeding habits of the southern elephant seal at Isla 25 de mayo / King George Island, South Shetland Islands

DANERI G.A.; CARLINI A.R.; MARSCHOFF E.; HARRINGTON A.

Buenos Aires

Conferencia; XXXI Reunión del Comité Científico Internacional de Investigaciones Antárticas (S.C.A.R) y 4th Open Science Conference; 2010

SCAR

The feeding habits of Mirounga leonina were analyzed at Isla 25 de mayo during 8 consecutive years (1995/6 to 2002/03). A total of 232 individuals were subjected to stomach lavage. The analysis showed that the diet was mainly represented by cephalopods followed by fish, their frequency of occurrence being 98.1% and 17.9 % respectively. The cephalopod diet indicated the dominance of the squid Psychroteuthis glacialis which occurred in 83% of samples and constituted 57.2% in numbers and 61.4% in mass. Octopods were of lesser importance occurring in 18% of samples. Juvenile seals fed on a lower variety of cephalopod prey than mature individuals did. Furthermore, octopods became more important in the diet of male individuals. This is in line with the differential diving patterns usually developed by the different sex-age groups of seals. The predominance of P. glacialis might be associated to the more southerly location of foraging areas of this population compared to others where this species is extremely abundant. As regards to the fish diet, this was mainly represented by the myctophid Gymnoscopelus nicholsi which occurred in 81.3% of stomachs containing otoliths and constituted 76.4% in numbers and 66.4% in mass. Another important fish taxon was the nototheniid Pleuragramma antarcticum, which occurred in 25% of samples and consituted 10% in numbers. It is suggested that while myctophids may be the dominant fish prey in areas close to the South Shetlands, they are probably replaced by P. antarcticum as seals migrate towards higher latitudes where this fish is abundant.