Improving detectability of illegal fishing activities across supply chains

Abstract Improving detectability (i.e., enforcers’ capacity to detect illegal fishing activities) is vital for fisheries management, food security, and livelihoods. Identifying factors linked to higher probabilities of illegal activities and their detection across supply chains is essential for effective interventions. Using a Bayesian Hierarchical Model and a large enforcement dataset from Chile, we evaluated determinants of detectability and violation probability across supply chain actors, species, regulations, and effort predictors. Our findings reveal an overall detectability rate of 7%, varying significantly across supply-chain actors. Notably, those higher in the supply chain, such as processors and restaurants—despite receiving less enforcement effort—show higher detection rates. This study offers insights to enhance detectability and improve enforcement targeting, particularly where budgets are constrained. Our approach complements technological advancements like satellite monitoring and supports strategies to reduce illegal fishing and promote compliance, contributing to better management and sustainability of fisheries in Chile and beyond.