Concentration and distribution of container flows in Mauritania’s maritime system (2019–2022)

Abstract

Small, trade-dependent economies often exhibit limited maritime connectivity, yet empirical evidence on the structural configuration of their container systems remains limited. This study analyzes route concentration and node distributions in Mauritania’s maritime container system during 2019–2022 using shipment-level data measured in forty-foot equivalent units (FFE). Routes, origin nodes, destination nodes, and industries are represented as FFE-weighted probability distributions, and concentration and divergence metrics are used to assess structural properties. Corridor concentration is pronounced across the six route classes (plus a residual category), with a Herfindahl–Hirschman index (HHI) of 0.296, and the top three account for approximately 84% of total FFE. Node structures differ by direction. Imports are associated with a highly concentrated set of destination nodes ( HHI = 0.848 ), while exports originate from only two origin nodes ( HHI = 0.567 ) and are distributed across a large number of destinations ( HHI = 0.053 ). Industry distributions are more concentrated for exports ( HHI = 0.352 ) than for imports ( HHI = 0.096 ), with frozen fish and seafood accounting for more than 53% of export volume. Over the four annual snapshots, route concentration moves within a narrow band ( HHI ≈ 0.293 –0.303) while node distributions vary more, particularly for export destinations (Jensen–Shannon distance, JSD, ≈ 0.395 ) and import origins ( ≈ 0.250 ); benchmarking these year-to-year distances against within-year resampling shows that corridor shares shifted slightly instead of holding fixed, and that part of the node-level variation is close to sampling noise. Because the window is short and overlaps the COVID-19 disruption, these results describe short-run persistence rather than long-run structural stability A complementary analysis of the directed flow graph reveals a pronounced hub-and-spoke architecture. Two domestic gateways (Nouakchott and Nouadhibou) concentrate most throughput and intermediation, the system separates into an import-supply block and a frozen-fish export block, and in a static structural sense, removing the single principal gateway would leave only about a quarter of current flow on unaffected arcs, providing an upper-bound indication of structural exposure rather than a forecast of realized disruption.