This study explores lobster fishing territory conflicts in the maritime provinces of Canada related to formal and informal rules governing access to harvesting areas. Game theory is used to analyze these territorial conflicts. The methodology is based on court decisions and media articles published over a period of almost 20 years (n=103), allowing us to represent the positioning of fishermen in a non-cooperative two-player game. These strategies have been grouped according to three levels of activity of the fishermen involved in the conflict. Some strategies are active, such as predation and retaliation; others rely on the assistance of a third party, whether it be the authorities or another third party. These two types of strategy are the most widely documented in the analysis. The third type of strategy is based on inaction. This type of strategy combines tolerance and avoidance. The identification of Pareto and Nash equilibria provides a better understanding of strategic interactions between players. Pareto equilibrium is achieved when both players choose passive strategies. Nash equilibrium is achieved when the first player chooses an active strategy, and the second player involves a third party. The player adhering to informal rules holds a strategic advantage, regardless of the conflict’s outcome. Therefore, fishermen who do not adhere to informal rules find themselves in a vulnerable position. The results highlight the importance of the regulator’s role in managing lobster fishing territory conflicts. The involvement of a third party can either mitigate losses or exacerbate tensions, depending on its capacity to act and the level of intervention provided. This research offers perspectives for the development of public policies promoting peaceful cohabitation in commercial lobster fishing areas by integrating formal and informal rules to address tensions and preserve community identity.