Whether they are called invasive, nonnative alien, exotic, or non-indigenous, introduced species are those that evolved elsewhere and have been purposely or accidentally relocated. While some species have invaded habitats on their own (e.g., migrating wildlife, plants and animals rafting on floating debris), human exploration and colonization have dramatically increased the diversity and scale of invasions by exotic species. Introduced species often find no natural enemies in their new habitat and therefore spread easily and quickly.

Invasive aquatic species have threatened the Great Lakes ever since Europeans settled in the region. Since the 1800s, more than 140 exotic aquatic organisms of all types - including plants, fish, algae and mollusks - have become established in the Great Lakes. As human activity has increased in the Great Lakes watershed, the rate of introduction of exotic species has increased. One third of invasive aquatic species have been introduced since the 1960s. Recreational boating, fishing, and international shipping ballast are the main pathways for invasive aquatic species to enter our lakes and waterways. The following species are of concern in our region’s waterways. 

Fish & Invertebrate

For more information on other aquatic invasive species found in the Great Lakes Basin, visit the Invading Species Program website

Common carp are domesticated ancestors of a wild form native to the Caspian Sea region and East Asia. Carp degrade shallow lakes by causing excessive turbidity, which can lead to declines in waterfowl and important native fish species. The common carp was introduced by unintentional release in 1879.

For more information on Carp:

Ontario Ministry of Natural Resources
Ontario Federation of Anglers and Hunters
Ontario Freshwater Fishes Life History Database

Carp

Sea lamprey are predaceous, eel-like fish native to the coastal regions of both sides of the Atlantic Ocean. They entered the Great Lakes through the Welland Canal about 1921. They contributed greatly to the decline of whitefish and lake trout in the Great Lakes. Since 1956, the governments of the United States and Canada, working jointly through the Great Lakes Fishery Commission, have implemented a successful sea lamprey control program.

For more information on Sea Lamprey:

Environment Canada
Ontario Freshwater Fishes Life History Database
Ontario Federation of Anglers and Hunters

Zebra mussels were first noticed in Lake St Clair in 1988 and have since spread throughout the Great Lakes and inland waterways like the Trent-Severn and Rideau Canal. They are native to Eastern Europe and Asia and likely entered North America through ship ballast. These small freshwater mussels grow up to 3cm long and settle on hard surfaces. Zebra mussels form dense colonies which out-compete native species and commonly clog water intake pipes.

Zebra Mussel Fact Sheet

Zebra Mussel Distribution Map

For more information on Zebra Mussels:

Great Lakes Science Center Factsheet  
Environment Canada
Ontario Ministry of Natural Resources
Ontario Freshwater Fishes Life History Database
Ontario Federation of Anglers and Hunters

Zebra Mussel

For additional information on invasive species visit Forests and Wetlands sections.

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