To what extent do marine-based economic activities influence the onset of violent conflict? Despite ongoing debate over several decades around the relationship between natural resources and violent conflict, little of the relevant research has addressed the marine environment. Based on satellite data in Indonesia, this paper exploited geographical variations in ocean productivity to provide new evidence on the relationship between fisheries and violent conflict. Using a search-by-radius approach, we compiled a sample of 757 cells to represent spatial interactions and spillovers between land-based conflicts and catch landings on the sea. We found that both industrial and non-industrial catches exhibit a statistically significant positive influence on the occurrence of conflict events. Additionally, increased illegal, unreported and unregulated (IUU) catches are more likely than legal catches to cause violent conflict. An increase in fish catches in Indonesian waters fuels conflict of every kind, among which protests and riots are most sensitive to fisheries while fighting and terrorism are least sensitive. Overall, these empirical findings support the hypothesis that increased competition for common-pool resources contributes to the onset of violent conflict.