A Brief History
On June 26, 1959, the St. Lawrence Seaway opened for commerce, bringing ocean going ships access to the Great Lakes. Consisting of a series of canals and 15 locks to bypass rapids on the river and Niagara Falls between Lake Ontario and Lake Erie, work on the system was started in 1954, although other canals had been dug much earlier.
Passing about 50 million tons of cargo per year, the Seaway has had tremendous positive impact on the industry and commerce of the Great Lakes and St. Lawrence region. Unfortunately, it has come at an ecological price. Opening passage by water to the Great Lakes has brought numerous harmful invasive species from the ocean and from other waterways throughout the world.
One of the most damaging of these invasive species have is the Sea Lamprey, a parasitic primitive eel like fish that killed off much of the native Lake Trout and Whitefish population before pesticides (larvacides used in rivers where they spawn) controlled them somewhat. They came via the Welland Canal, that opened in 1921 and is now part of the Seaway.
Other fish invaders include the White Perch, a smaller cousin of the more popular White Bass that is poorer table fare and is a notorious bait stealer. The Round and Tube Nosed Gobies that cover the lakes’ bottoms eat native fish eggs, reproduce many times per year, are too small to be sport fish and are also notorious bait stealers. Another invasive fish is the Ruffe, a fish from the Black and Caspian sea that grows to only about 5 inches, reproduces at an incredible rate, and is not particularly palatable to game fish.
Non-fish invasive species include the Zebra and Quagga Mussels that are familiar to Great Lakes and other boaters and fishermen as they quickly colonize new waters, covering every available surface, clogging boat motors and water intakes. Their filter feeding habits make the water much clearer, at first giving the impression they are doing some good, but in reality they are robbing baby fish and other native water-life of the tiny foods needed for growth. They also concentrate toxic chemicals, and in turn are eaten by some of the native fish, causing those fish to become contaminated with the toxins.
The Spiny Water Flea is not a flea, but a tiny crustacean with a stiff, bristle-like tail that is similar to a stiff hair. Out-competing native zooplankton, these critters are so rampant that they can coat and foul fishing lines of anglers. Although native fish will eat them, they are a poor food source and compete with newborn fish for food.
Almost everything humans do has an impact on the environment, and in the case of these invasive species a negative impact. Measures to control these invaders sometimes seem hopeless, and can cost vast sums of money. This is why it is better to prevent such problems first instead of trying to deal with them later. Question for students (and subscribers): What non-native invasive species do you find most annoying? Please let us know in the comments section below this article.
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For more information, please see…
Wildlife Forever. Invaders of the Great Lakes: Invasive Species and Their Impact on You. Adventure Publications, 2013.