Ballast water management - the control of harmful invasive species


Ballast water may be taken onboard by ships for stability and can contain thousands of aquatic or marine microbes, plants and animals, which are then carried across the globe. Untreated ballast water released at the ship’s destination could potentially introduce a new invasive marine species.  Hundreds of such invasions have already taken place, sometimes with devastating consequences for the local ecosystem. 

The International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention) was adopted in 2004 to introduce global regulations to control the transfer of potentially invasive species. With the treaty now in force, ships need to manage their ballast water.

Read more here.

Status of the BWM Convention

The BWM Convention entered into force on 8 September 2017.

BWM treaty requirements

Under the Convention, all ships in international traffic are required to manage their ballast water and sediments to a certain standard, according to a ship-specific ballast water management plan. All ships  have to carry a ballast water record book and an international ballast water management certificate. The ballast water management standards are being phased in over a period of time. New ships must meet the ballast water treatment standard. Existing ships should exchange ballast water mid-ocean but they will need to meet the ballast water treatment standard by the date of a specified renewal survey. Eventually, most ships will need to install an on-board ballast water treatment system.

Click here to read more about the requirements.

Approval of BWM systems

The BWM Convention requires that ballast water management systems used, to comply with the Convention, must be approved by the Administration taking into account the Guidelines for approval of ballast water management systems (G8). Read more here.

Capacity Building - GloBallast

IMO executed the GEF-UNDP-IMO GloBallast Partnerships Programme (2008-2017) to sustain the global momentum in tackling the ballast water problem and to catalyse innovative global partnerships to develop solutions. Click here to reach the official Website.
The GloBallast Story (download the PDF) outlines the key achievements of the GloBallast Partnerships Programme, executed by IMO in collaboration with the Global Environment Facility (GEF) and the United Nations Development Programme (UNDP). The project closed in June 2017. It was launched in 2007 after an initial 4-year phase and has been assisting developing countries to reduce the transfer of harmful aquatic organisms and pathogens in ships’ ballast water and implement the IMO Ballast Water Management (BWM) Convention.

The 10 most invasive species that can be transferred through ships’ ballast water are profiled in the publication, which also provides infographics, diagrams and detailed case histories.

Invasive species - a few examples


Asian Kelp (Undaria pinnatifida)

Better known as wakame, this edible seaweed is commonly used in Japanese and Korean cuisine. While native to cold-water coastal areas of Japan, Korea, and China, it has found its way to New Zealand, France, Great Britain, Spain, Italy, Argentina, Australia, Mexico and the US, where aggressive measures are underway to remove the plant from harbours on the western seaboard. The kelp was discovered in San Francisco Bay in May 2009.

Cholera (Vibrio cholera)

Port areas near the mouths of rivers are prime breeding ground for cholera bacteria, especially in countries where sanitation is poor and water has been heavily polluted with raw sewage. V. cholera bacteria attach to the surfaces of planktonic animals such as copepods (a type of small crustacean) and other zooplankton, particularly in tropical countries, as well as to shellfish and aquatic plants. By attaching themselves to waterborne microscopic organisms, the bacteria can enter ballast water and be transmitted to new areas around the world. If ingested in drinking water, strains O1 and O139 of the bacteria can cause cholera in humans.

European Green Crab (Carcinus maenas)

Another species colonising Australia is the European green crab, which has found its way from its original habitat in the north-east Atlantic Ocean and Baltic Sea to the Antipodes, South Africa, South America and both the Atlantic and Pacific coasts of North America. The green crab is a carnivore that preys upon clams, mussels, oysters, and gastropods. Its introduction to the US in the 1950s has cost the American fishing industry millions of dollars because the green crab preys on scallops and other commercially important shellfish. Aside from preying on native species, the European green crab is able to outcompete them for food, and can reproduce in high volumes. Research suggests that the green crab’s colonisation of estuaries in Washington, Oregon and British Columbia was facilitated by the El Niño storms of 1997 and 1998.

North Pacific Seastar (Asterias amurensis)

Native to Japan, North China, Korea and far eastern Russia, this starfish is capable of tolerating many temperatures and wide ranges of water salinities and is often found in estuaries and intertidal zones. Spawning between July and October, the female is capable of carrying up to 20 million eggs, which hatch and live as planktonic larvae for up to 180 days. The species has since been introduced to south-eastern Australia and Tasmania, most probably after having been carried as larvae in ballast water. The port of Melbourne is Australia’s biggest container port, handling many vessels inbound from the Far East. It is in Australia that North Pacific seastars are doing most damage. The creatures eat the eggs of the endangered handfish.