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 demand for fish (driven by food shortages) or decreased ability to fish (due to fuel scarcity, security concerns or damaged infrastructure), would affect global catches. We find a temporary negative climatic impact that intensifies with soot emissions, with global biomass and catch falling by up to 18±3% and 29±7% post-war under business-as-usual fishing. This decrease is similar in magnitude to 2090's declines under unmitigated global warming. Increasing demand results in annual to biennial catch increases, followed by precipitous decline with losses of up to 70%. In contrast , decreased ability to fish allows recovery of depleted fish stocks, creating decadal catch increases after initial decreases. Our results indicate that intensified fishing can only temporarily compensate for a very small fraction of agricultural food shortages. Management measures that rebuild the biomass of overfished populations can multiply the maximum possible fish catch, increasing mitigation of food shortages during global cooling events. This buffering function in the event of a global food emergency adds to the many benefits of effective and precautionary fisheries management.