Casting light on the workings of illegal fishing markets.

About 3.5 million fishing vessels ply the world's oceans, providing livelihoods and food for millions of people. Sound management is key to fisheries' sustainability, but illegal fishing, along with fishing overcapacity generally and environmental change, are putting many fisheries at risk. Illegal fishing is a globally pervasive yet unevenly distributed phenomenon, manifesting in diverse forms across both small-scale and industrial-scale fleets, the latter accounting for about 82 to 93% of the 8.4 to 15.4 million metric tons global annual illicit marine wild fish seafood trade valued at US$6.2 to 12.2 billion. The massive rise in fishing effort since 1950 has not been matched by adequate regulations and enforcement, especially for industrial-scale fishing in the waters of developing countries. About two-thirds of the illicit trade by value originates from fishing grounds in West Africa (27%), East Asia (24%), and Southeast Asia (16%). Remote sensing and AI technologies are improving detection of illegal fishing, but enforcement remains an issue given its high costs and the relative ease of laundering illegal catch through transshipments at sea, poorly regulated ports, and fraudulent documentation along seafood supply chains. Illegal fishing markets require multilayered policy responses grounded in transparency, international cooperation, and socioeconomic justice. Proposed measures, ranging from mandatory electronic vessel identification and subsidy reform to artisanal fishery protections and stronger port controls, warrant further research into their implementation and effectiveness.