The 'openMSE' package is designed for building operating models, doing simulation modelling and management strategy evaluation for fisheries. 'openMSE' is an umbrella package for the 'MSEtool' (Management Strategy Evaluation toolkit), 'DLMtool' (Data-Limited Methods toolkit), and SAMtool (Stock Assessment Methods toolkit) packages. By loading and installing 'openMSE', users have access to the full functionality contained within these packages. Learn more about 'openMSE' at <https://openmse.com/>.