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then be sent by air freight to registered facilities capable of testing ballast water and sediment samples to internationally acceptable criteria. At present no such testing facilities exist, and advanced biological analysis involving taxonomic identification to species level is both costly and time-consuming (see below). However, in principle, if shore-based analysis indicated that some form of treatment was required, the vessel could be notified accordingly. If the voyage passage time were long enough, treatment could be performed in transit.
A simplified version of this "sampling and dispatch" approach has been used by the Australian Quarantine and Inspection Service in the case of an identified chronic carrier of toxic dinoflagellate cysts operating between Japan and Australia. Extending the "sampling and dispatch" approach to a range of organisms of concern is a significant challenge in terms of both sampling and testing. In addition, critical ballast introductions—such as the Asian river clam in San Francisco Bay—would not have been recognized as significant potential invaders if they had been found and identified in ballast water samples prior to their introduction.
Under some circumstances, ports may choose to monitor their water to provide additional reassurance about the effectiveness of strategies used to manage ballast water in reducing the risk of introductions. For example, some port-water sampling studies have been conducted in Australia to determine the presence or absence of potentially harmful organisms that could be transmitted to other Australian ports (Kerr, 1994). Formal certification that a ballasting site (e.g., cargo discharge port) is, and continues to be, free of a given species requires a rigorous, continuing, scientific program (Carlton et al., 1995). Studies would need to be updated every three to five years—and possibly more frequently—to determine whether a species that was previously absent had been introduced.
Baseline sampling of ports for specific organisms to standardized, internationally accepted criteria would be helpful in determining the risk associated with a voyage between specified ports. The port of ballast water uptake could provide information that would assist vessel owners and operators in deciding upon the ballast water management or treatment methods needed during transit to meet requirements at the receiving port. This procedure could assist regulating authorities in more effective monitoring of possible introductions of a species known to be of concern. This approach would also require a costly, continuing program.
LEVELS OF MONITORING
The committee considered levels of monitoring for vessels in categories 1 and 2 (no ballast change conducted and ballast change conducted). When vessels have undertaken specialized onboard ballast treatment (category 3), monitoring of the method's effectiveness will be sensitive to the treatment class (see below). The three proposed levels of monitoring are as follows: