The Role of Oceanographic Features and Prey Distribution on Foraging Energetics and Reproductive Success of the Antarctic Fur Seal, Arctocephalus Gazella

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9726567 COSTA Marine coastal and pelagic environments of the Southern Ocean are characterized by seasonal high productivity. Over the last several decades it has become clear that these environments, while generally productive, also undergo considerable inter- and intra-annual variability. Consequently, available prey resources for vertebrate predators can be highly variable spatially and temporally. This spatial and temporal variability of prey resources has been measured empirically for the northern South Shetland Islands region of the Antarctic Peninsula since the late 1980's. The Antarctic fur seal, a sub-polar migratory otariid with a short lactation period, is an increasingly dominant marine predator of the South Shetlands region. Its life history is pattern is characterized by foraging trips alternating with short visits to provision a single offspring; this allows scientists to measure maternal investment on the same temporal and spatial scale as measurements of distribution and abundance of prey. This project will quantify the foraging costs and maternal investment associated with changes in strategies observed in populations of South Shetland Ataractic fur seals. Energetic costs and benefits of different foraging patterns with simultaneous measurement of energy expenditure, food intake, dive depth, dive duration, time of day, and dive frequency, swim speed and foraging location will be accomplished using state of the art techniques. These measurements will coincide with small and large scale oceanographic surveys to be conducted by the National Oceanic and Atmospheric Administration's Antarctic Marine Living Resources program, which is also contributing to the support of this project. The research will allow scientists to link biological characteristics (prey composition, distribution and abundance) and physical characteristics of the foraging environment with foraging success, maternal investment and reproductive success for a free-ranging marine ve rtebrate predator.