Alaska's Kenai fisheries are managed for maximum efficiency while ensuring fair allocation across multiple stakeholder groups and long term sustainability of the fishery. Managers must work to meet the fishery's goals while adapting their commercial and subsistence eco-service management practices to meet changing ecological conditions. Pre- and in-season fishery management practices are supported by historical and location-based management knowledge. Unexpected changes to environmental conditions may be outside the adaptive capacity of the management. Furthermore, managers currently lack a tool to test how proposed policy will alter fishery outcomes. We present an agent-based simulation framework designed for the Kenai case-study that incorporates stakeholder harvest and effort data, as well as Oncorhynchus nerka and Oncorhynchus tshawytscha salmon run-timing dynamics for the last 35 years. The resulting high-fidelity and verified model was used for scenario-based studies to understand how shifting ecological and social drivers effect the seasonal outcomes of fishery dynamics. Scenarios were determined from plausible future changes to system drivers identified during participatory stakeholder meetings and in scientific literature from southeast Alaska. Using our model, we uncovered recent instability in the Kenai fisheries coupled socio-ecological system dynamics, and determined equations that describe the strategy of fishery managers in responding to in-season drivers. Sensitivity of seasonal fishery outcomes to different drivers was quantified via the scenario-based studies. Our results show our agent-based simulation framework to be a capable decision support tool, one that resource managers might use for testing outcomes of proposed policy change in response to environmental change.