Modeling the Ecological Consequences of an Open-Sea Nuclear Release on Resident and Migratory Marine Fish in the North Atlantic

Accidental releases of radionuclides from nuclear-powered vessels or ships carrying nuclear weapons may expose marine organisms to radioactive contaminants. The consequences of such events can differ markedly between resident fish populations and migratory species that move through affected areas. While these contrasting responses have been evaluated by the authors for coastal nuclear accidents, comparable assessments for open-sea scenarios remain limited. We simulated radionuclide releases from vessels in the North Atlantic to evaluate exposure pathways and potential ecological effects on both resident and migratory fish, since several naval bases operating nuclear-powered vessels are located along the eastern North American coastline. Physical transport of radionuclides was modeled using a Lagrangian framework that incorporates advection by ocean currents, three-dimensional turbulent diffusion, radioactive decay, and dynamic sediment–water exchanges. This transport model was coupled to a four-compartment food-web bioaccumulation model representing phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish. The approach allows evaluation of contaminant uptake in resident fish populations and along the migration routes of highly mobile species. Bluefin tuna (Thunnus thynnus), a key ecological and commercially valuable species, was selected as the migratory case study. Migration paths reconstructed from electronic tagging data were integrated to estimate radionuclide exposure along individual trajectories. This combined modeling framework provides new insight into how open-sea nuclear releases may differentially affect resident fish communities and wide-ranging migratory species in the North Atlantic, with relevance for fish ecology, population risk assessment, and fisheries management.