Preliminary results from a study examining spatial structure and connectivity in Patagonian toothfish (Dissostichus eleginoides)
in the South Atlantic section of the Southern Ocean

Using the High Resolution laser-ICPMS at Old Dominion University, we sampled the edge of otoliths from Patagonian toothfish (Dissostichus eleginoides), and examined whether the elemental signatures could discriminate between geographic locations along the Scotia Arc and along the eastern South American continental shelf near the Falkland Islands. Furthermore, we examined the elemental signatures of material in the otolith nuclei, formed during the early life history: similar nucleus signatures can be expected between fish which were spawned on the same spawning ground, even if the samples have subsequently been taken from different locations. We found signatures on the otolith edge of fish from South Georgia and Shag Rocks showed distributions characterized by lower levels of Mn/Ca than samples from the FOCZ. Signatures from the nucleus showed separation between the fish from South Georgia and Shag Rocks, and fish caught further west, implying a stock boundary. Although fish caught off the eastern North Scotia Ridge showed nucleus signatures similar to FOCZ fish, the distribution of their edge signatures was similar to South Georgia fish, suggesting that the elemental signature is due to an environmental effect rather than a genetic one.