The Defense of the Great Lakes Against the Invasion of Nonindigenous Species in Ballast Water

Abstract

The Great Lakes is the first place where the United States has established a defense against the introduction of nonindigenous species carried in ballast water. U.S. regulations controlling the discharge of ballast from all vessels entering from outside the Exclusive Economic Zone into the Great Lakes went into effect in early 1993 and are enforced by the United States Coast Guard, with active assistance from the Canadians and the Seaway authorities. The Great Lakes are a unique, valuable, and sensitive resource which have already suffered significant damage from nonindigenous species and are under continuing threat from new invasions. The Great Lakes also have some unique defensive advantages because vessel traffic can be controlled at the Saint Lawrence Seaway and open ocean exchange with salt water can be used as a verifiable, reasonably cheap, and safe method for impeding the invasion of new freshwater species. However, more effective defenses are needed in order to prevent new invasions over the long term. Development of these new defenses will probably require engineering changes in ballast systems in all vessels engaged in transoceanic trade, whether going to fresh or saltwater ports.