Large commercial vessels routinely discharge ballast water, gray and black water, bilge water, and deck runoff consistent with applicable international and national standards. Ballast water discharges are a concern due to their potential to transfer aquatic invasive species from one location to another with consequent changes in regional and local ecosystems. Note that ballast water discharges and the invasive species issue is addressed under the "Invasive Species" discussion on this webpage. Accidental spills of oil and fuel can also cause significant damage to the environment and extensive standards have been put in place to prevent such accidents and to respond to such incidents when they do occur. Some specialized hull coatings that serve to prevent organisms from attaching to a ship's hull also release substances that are sometimes considered as vessel discharges. Shipboard management of garbage and other wastes generated on board vessels is addressed under Recycling, Reuse, and Waste Management.
Sewage, Gray water, and Other Discharges
Discharges of sewage (also known as black water) and gray water, which is the effluent generated from wash basins and showers on board ships, are regulated under MARPOL Annex IV as well as through specific restrictions established through national and local laws. Learn more
The Members of the World Shipping Council support an effective solution for managing ballast water discharges from vessels so as to minimize the environmental risk they present as a pathway for invasive marine species. The WSC has long advocated for the need for environmentally protective and economically achievable international standards for the treatment of ship's ballast water. Learn More
Spill Prevention & Response
International regulations for the prevention of oil pollution are set out in Annex I to MARPOL as well as the International Convention on Oil Pollution, Preparedness, Response, and Cooperation (OPRC) and its protocol covering pollution by hazardous and noxious substances (HPRC). To learn more, visit www.imo.org, and select Marine Environment, Prevention of Pollution.
All ocean-going commercial vessels utilize hull coatings designed to minimize resistance to movement through the water and the attachment of both soft and hard-shell organisms. These coatings are often referred to as "antifouling" coatings and are critical since they play a very important role in minimizing fuel consumption with a consequent reduction in CO2 emissions.
Some compounds employ "foul-release" coatings that are extremely slick and release fouling organisms as a vessel obtains specified operating speeds. Other compounds employ a self-polishing paint matrix that provides for a controlled release of specific biocides devoted to preventing the attachment of specific fouling organisms such as barnacles and slime.
Standards for the manufacture and use of these biocidal products are established through national regulations. In addition, the International Convention for the Control of Harmful Anti-fouling Systems on Ships (often referred to as the AFS Treaty) prohibits the use of organotins as an active antifouling agent and sets forth a structure for international restrictions on other antifouling compounds deemed to be harmful to the marine environment. The AFS Treaty eliminated the use of tributyltin (TBT) on ships in 2008 due its persistence in the marine environment and its effect on non-target species. To learn more, visit www.imo.org and select Marine Environment, Anti-Fouling Systems.