7.6 SOURCES OF BALLAST WATER DISCHARGED INTO VICTORIAN PORTS

For ships visiting Victorian ports, Walters showed that the sources of ballast for any one vessel may include a number of domestic and overseas ports, and that 45% of vessels which discharged ballast into Victorian ports were carrying ballast from more than one source³⁶⁶ It is possible, nevertheless, to assume that that vessels entering port with ballast water are likely to contain some ballast from their last port of call.

Walters documented the last port of call of all vessels entering Victorian ports over a 12 month period. This data shows that 29% of ballast water discharged into Port Phillip Bay was from international sources. The percentages of ballast discharged from international sources for Victoria's remaining ports are Geelong (38%), Hastings (10%) and Portland (72%). Table 13 shows the percentage of international and domestic ship visits to Victoria ports. Figure 7 shows total ballast water discharged in Victorian ports by vessels with an international or domestic last port of call from August 1994 to July 1995.

TABLE 13
Percentage of international and domestic ship visits to Victorian ports

Port	International	Domestic
Port of Melbourne	26%	74%
Port of Geelong	61%	39%
Port of Hastings	15%	85%
Port of Portland	72%	28%

Source: Data from Walters, S. (1996), Ballast Water, Hull Fouling and Exotic Marine Organism Introductions via Ships - A Victorian Study, Publication 494, Environment Protection Authority (Victoria)

FIGURE 7
Estimated ballast water received from vessels with an international or Australian last port of call, August 1994 to July 1995

Source: Data from Walters, S. (1996), Ballast Water, Hull Fouling and Exotic Marine Organism Introductions via Ships - A Victorian Study, Publication 494, Environment Protection Authority (Victoria).

Last ports of call for vessels entering Victoria are comprehensively documented in the report by Walters, and readers are referred to this report for detailed information. By way of a summary, the Committee includes details of the countries of origin and last Australian ports of call for vessels entering Victoria's ports in Section 7.7.

7.6.1 Movement of ballast out of Victorian ports

Destination ports of vessels departing Victorian ports were documented by Walters. The data emphasised the need for port ballast management plans to protect overseas, and other Australian and Victorian ports. For example, 68% of ships which departed Melbourne from August 1994 to July 1995 were sailing to other Australian states and territories. Given the presence of numerous exotic species in Port Phillip Bay, the Committee considers that other states and territories should be concerned about receiving ballast from the Bay.