To narrow their search of the more than five million square miles of Antarctic waters prowled by toothfish boats, Chakravarty overlaid three types of maps. Ice charts demarcated the ever-shifting melting line where the frozen, impenetrable Antarctic shelf ended and the thawed, navigable fishing waters began. Maritime maps indicated the patches of ocean that were beyond national jurisdiction. Nautical charts located the tallest and broadest of underwater plateaus where toothfish liked to congregate.
