In this study, oil spill development in the Istanbul Strait (the Bosporus) is numerically studied. The model is based on a flow field computed by finite element discretization of the shallow water equations. A stochastic Lagrangian particles cluster tracking approach is adopted for the simulation of the oil slick movement. It is shown that the timescale of a major spill is as,short as a few hours. The enormously increasing maritime traffic density alarms the development of environmental management tools for pollution prevention, prediction and risk assessment. The model we present for the Istanbul Strait extends our previous models by adding a stochastic approach and completes a mathematical prediction tool for this fragile environment.