Invasive species continue to be introduced to the Great Lakes from around the world. These non-native species are one of the greatest threats to the Great Lakes. By disrupting Great Lakes food webs and ecosystems, invasive species have severely impacted the ability of native fish to survive.

Invasive Species in Great Lakes

Invasive species are wreaking havoc on Great Lakes ecosystems and fisheries. More than 185 aquatic invasive species have entered the lakes, disrupting the food chain, fouling beaches and damaging infrastructure -- costing citizens, industry and businesses at least $200 million per year.

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

New invasive species are constantly being transported into the Great Lakes. A new non-native species is discovered on average once every 28 weeks.

Ocean-going shipping is the No. 1 source of non-native aquatic species entering the Great Lakes. The St. Lawrence Seaway connecting the Great Lakes to the Atlantic Ocean was opened in 1959. Since it was opened, 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 organism from ships' ballast tanks.

Ballast water exchange has not prevented the introduction of invasive species into the Great Lakes, because 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.

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.

An Environmental Protection Agency permit system requires ocean-going ships to engage in ballast water exchange. Unfortunately, ballast water exchange does not effectively eliminate invaders in the ballast tank.