Fish stocks are managed within national boundaries and by regional organizations, but the interdependence of stocks between these jurisdictions, especially as a result of larval dispersal, remains poorly explored.

This study combined oceanographic and life history data for 706 species and 434 genera of commercially harvested fish to estimate their connectivity across 249 EEZs and constructed a network representing the larval flows between nations.

It was found that the world’s fisheries are highly interconnected, forming a small-world network, emphasizing the need for international cooperation. The authors quantified as well each country’s dependence on its neighbors in terms of landed value, food security, and jobs. It was estimated that more than $10 billion in annual catch from 2005 to 2014 is attributable to these international flows of larvae.

It is highlighted that the economic risks associated to these dependences is greatest in the tropics, especially in terms of gross domestic product and labor force, however, a few European nations were also identified when considering food security.

Altogether, this study stresses the role of larval connectivity across international boundaries and the need for multilateral cooperation for sustainable management of these shared resources.

Ramesh et al. (2019) The small world of global marine fisheries: The cross-boundary consequences of larval dispersal. Science 364:1192-1196.