A subjective approach for ballast water risk estimation

There has been growing concern on the impact of established non-indigenous invasive species discharged through ships' ballast water into recipient port states and maritime communities. This concern has been addressed through legislative instruments at both national and international levels. In the absence of comprehensive, ballast water management plans, the Ballast Water Management Convention (2004) has made provision for the utilisation of risk assessment methodologies. Consequently, several risk assessment methodologies have been developed and applied in different ballast water research efforts. However, most of these methodologies adopt quantitative (probabilistic) approaches which are usually inadequate in addressing problems involving discharged ballast water and invasive species. A generic and robust model has been developed in this paper to deal with the problem of vagueness, uncertainty and inadequacy of data often associated with ballast water risk estimation. The model adopts a subjective (possibilistic) approach based on the application of fuzzy logic incorporated into the infection mode and effect analysis (IMEA) technique. (C) 2013 Elsevier Ltd. All rights reserved.