  We study a multi-agent system for the modeling maritime crime. The model
involves three interacting populations of ships: commercial ships, pirate
ships, and coast guard ships. Commercial ships follow commercial routes, are
subject to traffic congestion, and are repelled by pirate ships. Pirate ships
travel stochastically, are attracted by commercial ships and repelled by coast
guard ships. Coast guard ships are controlled. We prove well-posedness of the
model and existence of optimal controls that minimize dangerous contacts. Then
we study, in a two-step procedure, the mean-field limit as the number of
commercial ships and pirate ships is large, deriving a mean-field PDE/PDE/ODE
model. Via $\Gamma$-convergence, we study the limit of the corresponding
optimal control problems.
