Fishery management is the science of setting rules for governing fishing so that it is done in a sustainable manner. An ecosystem-based fisheries management (EBFM) approach has been advocated to recognize ecosystems as the complex systems that they are. If E B FM is to be put into effect, fishery managers require ecological models that take many factors into account to help them make management decisions. MS-PROD is one such model; it is a multi-species production model that forecasts the biomass of ten species of fish in the Gulf of Maine over 30 years. In the model, the biomass of each fish species depends on effects from harvesting and interactions with the other fish species. An interactive visualization of the model was designed and implemented to allow users to investigate the impact of changes in fishing effort in real time. By combining time series with a network representation, this visualization shows the predicted biomasses of the fish, the changes in biomass that can result from changes in fishing effort, the causal relationships that help to explain the effects of changes in fishing effort, and the uncertainty of the model. An evaluation was conducted to compare four different methods for depicting the two types of causal relationships in the model—predation and competition. The evaluation found that representing those relationships with arc diagrams enhanced the understanding of the model. This visualization is a novel combination of time series, a network diagram, user interaction, and a model. The visualization may be a powerful tool that could assist fishery managers in making informed decisions.