Even though many nations manage their fish stocks as if they were local resources, marine fisheries and fish populations are a single, highly interconnected and globally shared resource, a new study emphasizes.
This single resource transcends international management and economic zones due in large part to the dispersal of fish eggs and tiny larvae that can drift far and wide upon swift ocean currents, researchers report. The results of their global analysis of the international connectivity and economic contributions of more than 700 commercially harvested species worldwide reveals an ocean-spanning, “small-world” network within global fisheries.
According to the authors, such connectivity suggests that poorly managed fisheries or environmental disturbances in some critically important areas could have large economic implications on fisheries further afield and the millions of people who rely on the food and livelihoods they provide.
Many nations manage their fish stocks as if they were a local resource – independently and within internationally defined Exclusive Economic Zones (EEZs). Fish, however, care not for such arbitrary divisions and populations are often connected well beyond administrative boundaries. While this is particularly true for their itinerant larvae, the impact of larval connectivity across EEZs on fisheries is poorly understood.
Nandini Ramesh and colleagues used dynamic ocean modeling, network analysis and the life history data from 747 fished species to determine the dispersal larvae between EEZs. T
he results indicate that the international flow of larvae may account for substantial amounts of total marine catch – perhaps more than US $10 billion annually – underscoring the economic risks associated with a nation’s dependency on EEZs outside of their jurisdiction.
According to Ramesh et al., it’s this interdependence of fisheries across the globe that forms a single, global network characterized by tight interconnections and particularly important hubs of productivity.