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More than 185 aquatic invasive species have entered the Great Lakes, disrupting the food chain, fouling beaches and damaging infrastructure -- costing citizens, industry and businesses at least $200 million per year. Most of these species were transported into the Great Lakes in the ballast water tanks of ocean-going ships.

Invasive species are one of the worst problems facing the Great Lakes. Effective controls on invasive species are necessary to protect the future of Great Lakes wildlife, recreation, fisheries and economy.

Ballast Water -- Invasive species' free ride to the Great Lakes

Ocean-going shipping is the No. 1 source of non-native aquatic species entering the Great Lakes. A new non-native species is discovered on average once every 28 weeks.

Since the St. Lawrence Seaway connecting the Great Lakes to the Atlantic Ocean was opened in 1959, 85 invaders have been discovered and 54 are linked to ballast water discharge. A few invasive species, including the Asian carp, are transported in methods other than ballast water.

Attempts at controlling ballast water introductions

Since 1993, ocean going ships have been required to replace their ballast water with ocean water before entering the Great Lakes. This process is known as ballast water exchange. Unfortunately, it does not fully eliminate non-native organisms from ships' ballast tanks.

Non-native organisms can remain in the crevices of the ballast tank and in the layers of sediment in the bottom of ballast tanks. The average rate of discovery of invasive species in the Great Lakes has not declined since ballast water exchange became mandatory.

Though many freshwater organisms cannot survive in salty ocean water, others can survive in both fresh and ocean water. When ballast tanks empty most of their freshwater at sea and bring in ocean water, some species are able to survive in the new moderately salty ballast water.

Our Work to Keep Invasive Species Out of the Great Lakes

The National Wildlife Federation is engaged on multiple fronts to protect the Great Lakes from invasive species. We are working for more effective invasive species regulation by the Environmental Protection Agency; stronger water quality and invasive species programs in Great Lakes states; and strong federal legislation that protects the Great Lakes permanently.