Risk Assessment in Ballast Water Management - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 161

uncritical, and hence the level of risk is lower than intermediate, but still not
acceptable for unmanaged ballast water discharges, however,

- if a HAOP is present also in the recipient port and was included in a control pro-

gram, this means that it was perceived and selected by the port State as critical.
Therefore, the level of associated risk is extreme.

If a port State has selected target species which it does not want to become dis-
charged in its jurisdictional waters, then these by default trigger the extreme risk
should these species occur in the donor port or region. Target species are selected
based on selection criteria (see section “ Species-specifi c method ”). The species'
biogeographical method is considered through the target species selection.
When considering human pathogens, these are certainly one of the most unwanted
species, and therefore have also been selected to trigger the same level of extreme
risk. In the case of toxic algae, the approach is split in two levels. In many cases,
these are present in ports as resting stages in sediments and may not cause blooms.
However, these can be loaded on board ships with ballast water. This may occur
when sediments are stirred-up in the water column so that some resting stages of
toxic algae may also be present in the ballast water, and therefore have been selected
as posing a high risk. In case these algae are in the bloom state, these will certainly
be loaded on board the vessel within the ballast water in millions and possibly form
resting stages in the ballast tank to survive the voyage. Hence, they represent a seri-
ous threat to the ballast water recipient environment and have also been selected to
trigger extreme risk. After a vessel has loaded ballast in an algal bloom state, it may
be expected that water and/or sediments inside a ballast tank will have a great poten-
tial to contain harmful algae, which may last for a longer time, i.e., also multiple
ballasting operations in their next ports of call may not remove those organisms
completely. Therefore, the cleaning of tanks and notifi cations issued by port State
authorities to vessels in case of harmful algal blooms is critical.

Risk Assessment Model for Selective Ballast Water Management
Measures

The discharge of ballast water will be deemed as posing a low risk in

conditions when:

- the ballast water is moved between ports with freshwater (<0.5 psu) and fully

marine conditions (>30 psu), independent of whether the donor and recipient
ports are in the same region; or

- the ballast water is from a donor port that does not contain HAOP and is from the

same region as the recipient port.

The discharge of ballast water will be deemed as posing an intermediate risk in
conditions when: