Ballast water discharges are an important vector for the introduction of harmful aquatic organisms and pathogens into an area and can cause extensive damage to aquatic ecosystems.
Ballast water operations are used to compensate for increased buoyancy when a vessel is not fully laden or to compensate for a non equal distribution of cargo, adverse weather conditions, approaches to shallow water or for fuel consumption during a voyage. Thus a vessel will take on huge quantities of water in one port which will be discharged into another port when more cargo is loaded, transporting species away from their native environment. It is therefore critical to be able to accurately assess the quantity of discharged ballast water, preferably in advance of a vessel’s arrival in a port to enhance the management process and enable port authorities to respond timely with adequate measures.
In the EU, different ballast water management (BWM) approaches have been developed at regional levels and are of voluntary nature (HELCOM / OSPAR / REMPEC BWM approaches). However, a common and mandatory EU wide BWM approach has not yet emerged.
Ballast water as a transport vector of aquatic species was initially addressed in a 1973 International Maritime Organization (IMO) resolution. As a consequence, IMO worked towards the finalisation of the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) which was adopted in 2004 setting global standards to prevent transfers of harmful aquatic organisms and pathogens by vessels ballast water.
The BWM Convention introduces two different regimes with a sequential implementation:
Ballast Water Exchange Standard (Regulation D-1) requiring ships to exchange a minimum of 95% ballast water volume;
Ballast Water Performance Standard (Regulation D-2) which requires that ballast water discharged has the number of viable organisms below specified limits.
At present it is believed that the only way to achieve the discharge requirements of the D-2 standard is with the installation of a ballast water treatment system which will involve additional costs.
However, the BWM Convention will only enter into force 12 months after 30 states have ratified the BWM Convention representing 35% of the world merchant fleet gross tonnage. As of April 2014, 38 states have ratified the BWM Convention, representing 30.4% of the world merchant fleet gross tonnage. Once the convention comes into force VECTORS will have several tools ready (e.g., BWM risk assessment and decision support systems) to support this.
VECTORS produced a generic ballast water discharge assessment model which was based on vessel cargo operations and dimensions. This model was tested considering real shipping traffic and ballast water discharge data for the Port of Koper, Slovenia. The results show high confidence that the model predicts correctly whether or not a vessel will discharge ballast water, as well as assessing the quantity of ballast water to be discharged.
The risk assessment developed in VECTORS strictly follows the BWM Convention and is the most recently prepared global BWM related risk assessment. It enables a selective BWM so that only those vessels carrying critical ballast water are required to conduct BWM. Three different BWM risk assessment methods are utilised; “environmental matching”, “species’ biogeographical” and “species-specific” risk assessments.