The Guidelines noted that the ability of aquatic organisms and pathogens to survive after transportation may be reduced by insignificant differences in prevailing ambient conditions, such as salinity, temperature, nutrients and light intensity. They recommended care in loading ballast water to ensure only clean water and clean sediments were taken on board.
Where the non-discharge of ballast water was not possible, ballast water exchange in the open sea provided a means of limiting the introduction of unwanted species. Deep ocean water contains few organisms and those that do exist are unlikely to adapt readily to a new coastal or fresh-water environment.
Other ballast water management practices could be acceptable. The guidelines highlighted possibilities for the future, such as treatment by chemicals and biocides; heat treatment; oxygen deprivation; tank coating; filters; and ultraviolet light disinfection. In the longer term, changes in ship design may help limit the uptake of unwanted pathogens and organisms in ballast water.
UNCED 1992
The problem of non-indigenous species introduced by ballast water in ships was also being recognised by broader environmental forums.
The United Nations Conference on Environment and Development (UNCED), in Rio de Janeiro 1992, recognised the issue as a major international concern.
The Conference urged states to assess the need for additional measures to address degradation of the marine environment from shipping in12 different ways, including "Considering the adoption of appropriate rules on ballast water discharge to prevent the spread of non-indigenous organisms". 1
Back at IMO, the MEPC at its 33rd session in October1992 established an informal working group to discuss papers on ballast water presented by Australia. The MEPC endorsed a proposal by the group to establish an intersessional correspondence group which would conduct a survey on ballast water and look at the extent to which the1991 Guidelines were being implemented.
The correspondence group included United States, Canada, United Kingdom, New Zealand and Japan, with Australia as the lead country.
1993 Ballast water survey
In 1993, Australia presented the results of the ballast water survey to the 34th MEPC session.
The survey, based on replies from13 countries, noted: "The introduction of exotic organisms and/or species is having a major economic impact on the marine environment, aquaculture and other industries in some countries. In some cases, aquaculture farms have been closed several times. This has resulted in financial loss to the industry, the people working in the industry and ultimately to the national econo my. The whole New Zealand shellfish industry was closed to domestic and export markets due to a toxic algal bloom."
The report noted that alien species, once established, may spread rapidly. "Invariably, once a species becomes established it is impossible to remove it, and control of the organisms can become a very expensive exercise, as best evidenced by the experience of Canada and the United States with the Zebra mussel in the Great Lakes, the introduction of which is estimated to cost those nations US$5 billion by the year 2000."
The report also highlighted the rapid spread of the Japanese seaweed Undaria pinnatifida along Australia's Tasmanian east coast - with disastrous effects on the abalone industry and presenting a threat to oyster and mussel farms.
1 Paragraph 17.30(a)(vi) of Chapter 17 of Agenda 21. Agenda 21, adopted by UNCED, "addresses the pressing problems of today and also aims at preparing the world for the challenges of the next century. It reflects a global consensus and political commitment at the highest level on development and environment cooperation." Agenda 21 Chapter 17 "Protection of the Oceans, All Kinds of Seas, Including Enclosed and Semi-enclosed Seas, and Coastal Areas and the Protection, Rational Use and Development of their Living Resources" can be found on the Internet at: http://www.igc.apc.org/habitat/Agenda21/ch-17.html
