introductions of nonindigenous aquatic organisms, the U.S. maritime industry should pursue implementation of a combination of practices for managing ballast water and the control options described herein, within the framework of existing international guidelines.

Recommendation for the member states of IMO. Future international considerations should include establishing guidelines for baseline sampling of ports for specific organisms. Samples should be tested to agreed-upon international standards to facilitate comparisons of the water of each ballast uptake port with the water of receiving ports.

Recommendation for the member states of IMO. In future discussions and updates of the existing voluntary guidelines (IMO Assembly Resolution A.774(18), 1993), further consideration should be given to the maintenance of appropriate ships' logs and records of ballast water movements and any management practices used. These data could be valuable when used in conjunction with measurements of basic water-quality parameters to verify that ballast water has been effectively managed.