Sentences with phrase «exchange ballast water»

In 1991, the IMO adopted guidelines which recommend that ships should avoid taking on ballast in shallow areas and during toxic blooms of marine algae; keep accurate records of where and when ballast is loaded; exchange ballast water at sea, where toxic organisms are rare; and discharge sediments into approved areas at the port of destination («End of the line for deadly stowaways», New Scientist, 24 October 1992).

To prevent maritime invasions, some countries require ships to exchange their ballast water in midocean.