VESSEL TRAFFIC MOVEMENT

SHIPS are specifically designed and built to move safely through the water while carrying cargo. But when travelling either without cargo or only partially laden, ships must take additional weight on board to enable them to operate effectively and safely. This weight, known as ballast, is crucial to maintain safe operating conditions in shipping voyages as it reduces stress on the hull, provides transverse stability, improves propulsion and manoeuvrability, and compensates for weight lost.

Cross section of a ship showing ballast tanks and ballast water cycle (left). According to the International Maritime Organisation (IMO), the spread of invasive species in ship’s ballast water is largely due to expanding global trade and traffic volumes.

Although essential for shipping operations, ballast water may pose serious ecological, economic and health problems from the multitude of marine organisms/species carried from one port to another. Species that have been moved, intentionally or unintentionally, due to human activity into areas where they do not occur naturally are called ‘introduced species’ or ‘alien species’.

The International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM) was adopted at a Diplomatic Conference held at the International Maritime Organisation (IMO) Headquarters in London on 13 February 2004. The Convention will enter into force 12 months after ratification by 30 states with 35 % of world merchant shipping tonnage. As of 31 October 2012, 36 countries representing about 29 % of world tonnage have ratified the Convention. As only about 6 % of world tonnage needed to fulfil these requirements remains, it is envisaged that the Convention would soon come into force. Malaysia ratified the Convention on 27 September 2010.

 With more than 70,000 ships passing through the Straits of Malacca annually making it one of the busiest shipping lanes in the world, the threat of marine environment contamination from ballast water is serious and needs proper management and regulation.

Several strategies have been developed and used globally, often including one or several of the following:

• ·         Minimising uptake of organisms into ballast water tanks by avoiding ballast water uptake in shallow and turbid areas for instance in areas where propellers can stir up sediment, and avoiding uptake at night when many organisms migrate vertically in the water column to feed to reduce the number of organisms that enter ballast water tanks.
• ·         Removing ballast sediment through routine cleaning of ballast water tanks and removal of sediment in mid-ocean or at specific facilities provided at ports to reduce the number of organisms that could potentially be transported.
• ·         Avoiding unnecessary discharge of ballast water. In circumstances where cargo handling demands uptake and discharge of ballast water within a port, water taken up in another area should not be discharged if possible.
• ·         Conducting ballast water exchange either between ports, mid-ocean or in deep water to reduce the risk of invasions.