Frequently Asked Questions (FAQs)
Ballast Water
What is ballast water?
What are the potential problems associated with ballast water?
What is the Scottish Government doing to minimise introductions of non-native species?
What is ballast water?
Ships use ballast water to adjust their stability and trim when sailing without cargo or only partially loaded. This is important both for safety reasons and for the economic operation of vessels in the modern shipping industry.
It is estimated that more than 10,000 million tonnes of ballast water are transported by shipping activities (worldwide). Ballast water discharges in the vicinity of Scottish Ports accounts for over 26 million tonnes of this total.
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What are the potential problems associated with ballast water?
The use of ballast water can present serious consequences to the marine environment through the accidental introduction of non-native species when ballast water is discharged in harbours or coastal waters. Scientists estimate that more than 3,000 species of fauna and flora are in transit every day in ships ballast water. While many may not become established in their new environment, or may be harmless, others can have detrimental effects. For example, introduced species can transform ecosystems, alter natural habitats and threatened native and endangered species through competition for food, habitat and resources. They can also cause significant damage to economic interests such as fishing and may affect public health through the occurrence of harmful algal blooms.
While there is no firm evidence to date to suggest that ballast water discharges have resulted in species introductions within Scottish waters, there have been three recent concerns surrounding potential ballast water transfer:
- Possible transfer of the parasite Gyrodactylus salaris from Norway. This parasite affects salmon and trout populations, causing concern for Scottish fisheries and aquaculture.
- Possible transfer of phytoplankton that can form harmful algal blooms or 'red tides'. The public health implications are well documented and include Paralytic Shellfish Poisoning (PSP) which can cause severe illness in humans.
- Scientific research has shown that human pathogens may be transported in ballast water of ships including the cholera bacteria Vibrio cholerae.
It should be noted that there is no evidence to support their transport in ballast water to Scottish waters.
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What is the Scottish Government doing to minimise introductions of non-native species?
The International Maritime Organisation (IMO) held a conference in 2004 at which an 'International Convention for the Control and Management of Ships Ballast Water and Sediments' was agreed. The Scottish Government is working alongside Fisheries Research Services - Marine Laboratory (FRS-ML) and the Maritime and Coastguard Agency (MCA) to review ballast water treatment and management methods.
A variety of treatment and management methods are currently under development in the UK, including the use of filtration, ultra-violet, heat and ultrasound treatments as a means of reducing non-native introductions. These options are some way off being ready to apply on a large-scale, therefore it is likely that future policy will focus on ballast water standards that management or treatment methods will have to achieve.
Existing IMO guidelines on ballast water introductions have focused on preventative methods, with exchange of ballast in mid-oceanic water being the only recommended method currently available to reduce the level of non-native species introductions.
Further information on ballast water introductions can be found at MARTOB, FRS-ML and IMO.
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