Ballast Water Risk Indication for the North Sea

The ballast water from ships carries marine organisms that have invasivepotential. The International Maritime Organization Ballast WaterManagement Convention (2004) requires ballast water exchange orballast water management (BWM) systems either onboard or ashore.Ships can be exempted on the basis of risk assessment, when exclusivelysailing between specific ports or in an enclosed area. In reply to ourquestionnaire, the shipping sector argues that the North Sea isecologically homogeneous and exemptions could therefore be granted.This paper proposes that the North Sea area is, in fact, not homogeneousin terms of hydrographical and biological conditions; therefore, ballastwater is a relevant transport mechanism for organisms. Within the NorthSea, the short shipping routes indicate a high risk for survival. Weexamined actual simulation models for ballast water risk assessment inthe North Sea, and we have identified the major parameters that need tobe included in such models. These models provided a basis; they furtherneed to be combined and adapted for the purpose of evaluating therationale for an exemption. We concluded that exemptions from BWMare not recommended for the North Sea area. Anticipating the BallastWater Management Convention, ship owners might do well to studypossibilities for installing BWMsystems onboard