| Abstract : |
Antarctic fur seals over winter in warmer waters north of the Antarctic Convergence. There, pregnant seals forage continuously, storing fat for their return to Antarctic breeding sites in summer. Once on these seasonally ice-free islands, they nurse their young with milk generated from fat stores obtained by ingestion of a broad range of prey species. Stable nitrogen isotope (δ15N) analysis of the protein in the seals? milk allows us to estimate the foraging ecology and movement patterns of these seals. While living and foraging in the more northern areas, the seals primarily consume several species of fish with higher δ15N values, leading to correspondingly higher δ15N values in the seals' tissues. . When south of the Antarctic Convergence, seals often feed on abundant Antarctic krill that have lower δ15N values, which would also be reflected as lower δ15N values within the seals' tissues. It is not yet known whether Antarctic fur seals travel from their overwintering, northern waters directly to their breeding islands fueled entirely by fat stores accumulated in winter, or whether they forage as they migrate, consuming krill in the process. The goal of this project is to use stable isotope analysis to determine if the seals forage on krill before giving birth. The results will provide evidence for the importance of krill in the diet of Antarctic fur seals prior to pupping and breeding and the potential for conflict with krill harvesting by humans. |