Marine wild-capture fisheries after nuclear war

Nuclear war, beyond its devastating direct impacts, is expected to cause global climatic
perturbations through injections of soot into the upper atmosphere. Reduced temperature
and sunlight could drive unprecedented reductions in agricultural production, endangering
global food security. However, the effects of nuclear war on marine wild-capture fisheries,
which significantly contribute to the global animal protein and micronutrient supply,
remain unexplored. We simulate the climatic effects of six war scenarios on fish biomass
and catch globally, using a state-of-the-art Earth system model and global process-based
fisheries model. We also simulate how either rapidly increased fish demand (driven by food
shortages) or decreased ability to fish (due to infrastructure disruptions), would affect
global catches, and test the benefits of strong pre-war fisheries management. We find a
decade-long negative climatic impact that intensifies with soot emissions, with global
biomass and catch falling by up to 18 ± 3% and 29 ± 7% after a US-Russia war under
business-as-usual fishing – similar in magnitude to the end-of-century declines under
unmitigated global warming. When war occurs in an overfished state, increasing demand
increases short-term (1-2 year) catch by at most ~30% followed by precipitous declines of
up to ~70%, thus offsetting only a minor fraction of agricultural losses. However, effective
pre-war management that rebuilds fish biomass could ensure a short-term catch buffer large
enough to replace ~43 ± 35% of today’s global animal protein production. This buffering
function in the event of a global food emergency adds to the many previously-known
economic and ecological benefits of effective and precautionary fisheries management.