Abstract
<title>Abstract</title> <p>Maritime supply chains carry most internationally traded food, yet the conditions under which trade diversification protects supply against disruption remain poorly understood. This paper asks when re-routing trade through substitute corridors restores resilience and when it fails. We model U.S. seafood trade—the largest national seafood import market—as twenty bilateral shipping corridors, each a Belief–Desire–Intention agent that defends a five-pillar Food Supply-chain Resilience (FSR) index built on the FAO food-security dimensions and chooses monthly between within-corridor hedging and re-routing displaced volume to substitute corridors through an auction for finite shared absorption capacity. The model is calibrated to 3,880 corridor-months spanning 2010–2026 and eight policy eras, and reproduces two distinct regimes. When shocks are bilateral, spare capacity is available and corridor switching restores resilience; when shocks are simultaneous and multilateral, shared capacity is exhausted by congestion and switching fails, so resilience depends instead on the pre-existing structure of trade relationships. For each product and regime, optimisation identifies the corridors that maximise FSR. The finiteness of shared substitution capacity distinguishes conditions under which diversification does and does not deliver resilience, with implications for trade and supply-chain policy under simultaneous shocks.</p>