Risk Assessment in Ballast Water Management - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 156

Fig. 4 Basic principles for the RA for exemptions

￿ Salinity is the only enough reliable parameter for the environmental matching RA.
￿ RA would result in acceptable low risk only if the donor and recipient ports are
located one in freshwater (<0.5 psu) and the other in fully marine conditions
(>30 psu).
￿ If the donor and recipient ports are located one in freshwater (<0.5 psu) and the
other in polyhaline conditions (>18 psu), than a combined approach with species-
specifi c RA is needed to consider high salinity tolerant species.