Southern elephant seals (Mirounga leonina) are top predators of the Southern Ocean and adjacent ecosystems, where they plan an important ecological role over large spatial scales (millions of km² as consumers of squid and fish. Although there is a considerable amount of information on elephant seals throughout their circumpolar distribution, interactions within the western Antarctic Peninsula (WAP) environment are poorly characterized. A total of 56 adult female elephant seals (2005-2009) were instrumented with Sea Mammal Research Unit (SMRU) Satellite Relay Data Loggers-CTD tags to determine at-sea location, diving behavior, and temperature and salinity of the water column. The analysis of the tracking and diving behavior data allowed us to determine at-sea distribution, movements, and foraging patterns and foraging success, identify the specific oceanographic features and/or habitat used by foraging seals, and compare seasonal and annual changes in foraging behavior and habitat-use in relation to changes in oceanographic conditions. In addition to providing data on the foraging behavior of the seals relative to oceanographic features, these animals are collecting measurements of the physical environment in poorly sampled regions. The diversity in foraging strategies observed in the tracking data was confirmed using stable isotops (δ¹³C and δ¹⁵N), which showed that animals from the WAP exhibit partitioning of both habitat and prey resources. Multivariate analysis of the isotopic data allowed the identification of different foraging strategies, even within the same environment (e.g., shelf foragers) that were not apparent when analyzing the tracking data alone. The results suggest elephant seals from the WAP display a diversity of strategies to exploit a diverse range of oceanographic conditions.

Luis Hückstädt received Magister en Ciencias con mención en Oceanografía from the Universidad de Concepción, Chile in 2003. He is currently a Ph.D. student at the University of Santa Cruz, California. He is working with Dr. Dan Costa on a NSF-funded research project that is focused on understanding habitat use and foraging behavior of elephant, crabeater, and leopard seals along the Western Antarctic Peninsula. This work is a continuation of research started during the Southern Ocean GLOBEC field studies.

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