A key purpose of an MSE is to compare the performance of alternative management approaches, or Management Procedures to identify the method that is most likely to meet the management objectives for a fishery.

In essence, a Management Procedure is simply a set of rules which define how a fishery will be managed. These rules can range from simple harvest policies to more complex arrangements.

For example, a simple Management Procedure may be a constant catch policy, where the annual total allowable catch (TAC) is set a some fixed value. Alternatively, a more complex Management Procedure may involve multiple data sources, with rules that increase or reduce the TAC in response to trends in one or several indicators.

Management Procedures can differ in data requirements and complexity. However, all Management Procedures have one thing in common. They take fishery information and return a management recommendation.

To be included in an MSE, a Management Procedure must be reproducible and able to be coded in a set of instructions. While fisheries are sometimes managed by expert judgment, it is difficult to reproduce the subjective decision-making process in a computer simulation and include such methods in an MSE.

The MPs are functions of class MP that take an object of class Data and return an object of class Rec which contains the management recommendation(s).