Management strategy evaluation (MSE) is a tool that scientists and managers can use to simulate the workings of a fisheries system and allow them to test whether potential harvest strategies—or management procedures— can achieve pre-agreed management objectives. In so doing, MSE helps to determine the harvest strategy likely to perform best. That means the strategy would perform well, regardless of uncertainty, and balance trade-offs amid competing management objectives. Around the world, fisheries are moving toward management based on harvest strategies to increase long-term sustainability, stability and profitability. MSE must be an integral component of the process to ensure that the chosen strategy can achieve its objectives.