Download the world trade data for fish and fish products as a
GDF file. Load it into Gephi. Apply a filter (Filters->Edges->Edge weight ... drag to Queries, click on Filter) such that only edges are kept where at least 5% (weight = 0.05) of the country's imports of fish stem from the other country. Calculate betweenness by clicking on Statistics -> Av. Path. Length -> Run. Check out the betweenness values in the data laboratory view. Among the choices, the country with the highest betweenness is: