Risk Assessment in Ballast Water Management - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 144

donor port(s), port region and biogeographic region, not present in the recipient
port, to allow identifi cation of target species;

- the presence of all target species in the recipient port(s), port region, and biogeo-

graphic region;

- the difference between target species in the donor and recipient ports, port region,

and biogeographic region;

- life history information on the target species and physiological tolerances, in

particular salinity and temperature, of each life stage; and

- habitat type required by the target species and availability of habitat type in the

recipient port.

Even when a target species has been reported, although its establishment status
and abundance may be unknown, from the donor and recipient ports, its continued
introduction into the recipient port(s) may increase the probability that it will
become established and to cause negative impacts. This is especially the case when
the target species occurs in higher abundance in the donor port compared to the
recipient port.
As a starting point, a simple assessment may be conducted to evaluate whether a
target species is present in the donor port, but not in the recipient port, and if it can
be transported via ballast water. In a more comprehensive approach the following
points may need to be evaluated (IMO 2007 ):

- Uptake - probability of viable stages entering the vessel's ballast water tanks

during ballast water uptake operations;

- Transfer - probability of survival during the voyage;

- Discharge - probability of viable stages entering the recipient port through ballast

water discharge on arrival; and

- Population establishment - probability of the species establishing a self-

sustaining population in the recipient port.

An even more detailed scenario would be to determine the likelihood of a
target species to survive each of the stages listed above. However, the required
data may only be available in rare cases, especially when considering that all
life stages of the target species need to be assessed also including seasonal vari-
ations in the target species presence in the donor port with seasonal conditions
in the recipient port to meet the species abiotic tolerances (e.g., temperature and
salinity). Consequently, the overall RA of unmanaged ballast water discharges
should be determined based on the evaluation of all target species surviving all
these stages.
To groundtruth the chosen species-specifi c RA approach, data may be gathered
for already introduced species in the recipient port. This is to check whether or not
the RA approach selected would have predicted this species to be able to survive in
the ballast water recipient port. A failure to predict existing invaders correctly may
indicate that the model under-predicts the risk, noting that species may have arrived
by various vectors.