Overfishing is the main threat to sustainable fisheries and the loss of marine biodiversity. The race-to-fish phenomenon is a central driver of overfishing, and it prevails from small-scale to large-scale management regardless of whether spatial-right-based fisheries management has been implemented to ensure the ownership of fishery resources. In practice, the fishing grounds of resource users create complex configurations. Systematic understanding of harvesting competition across these configurations is necessary to promote sustainable fisheries management. Here, we developed a spatially-explicit model to analyze various scenarios of harvesting competition between two user groups using a game-theoretic approach. We found that realized harvesting competition was largely determined by the configuration of fishing grounds and an ecological mechanism where the ecological rescue effect could escalate harvesting competition, leading to a low population size. Our results also suggested that the implementation of voluntary no-take marine protected areas could largely mitigate harvesting competition. This suggests that the coordination of user groups is essential to resolve the race-to-fish. •Harvesting competition is the central driver of overfishing.•The intensity of harvesting competition depends on fishing ground configuration.•Ecological mechanisms also characterize harvesting competition.•The creation of collaborative no-take MPAs can substantially reduce competition.