How to Identify Invasive Fish in Ontario
Ontario is bordered along most of its southern edge by the Great Lakes. These vast repositories hold about 90 percent of the fresh water in North America. Water drains into the lakes from many directions. Locks and canals have been built to further build out the connections to other water systems, including the Saint Lawrence river that empties into the sea. Invasive species have arrived in the lakes not only by swimming but by being transported, both by people who are fully aware of what they are doing or in ships accidentally. The lake ecosystem has seen considerable change as a result.
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Instructions
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Identify the sea lamprey by its long eel-like body, and circular mouth full of rasping teeth. You will see them attached to trout and whitefish, native species in the lakes. Lampreys are native to the ocean, and entered the Great Lakes through the Welland Canal.
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Identify the common carp by its large heavy scales. The body shape is recognizable by anyone who has seen Japanese koi goldfish in a pond. Koi are simply colorful carp. Carp stir up turbidity by pushing through the mud looking for food. They are also very efficient predators and can empty an area of native baby fish. Carp were introduced by various accidental releases, and are now common in many spots in North America.
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Identify the northern snakehead by its size, which can reach almost two meters, it's wide mouth full of very sharp teeth, and long dorsal and anal fins which run much of the length of the fish. They have been found in a number of locations in the United States and recently one was caught in an Ontario river. They are voracious predators, survive in cold, shallow and muddy water, and can actually cross short distances of dry land to reach new homes. These fish were purchased for aquariums or food and then were dumped into ponds and rivers when they became too big.
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Identify zebra mussels by their small, zebra-striped shells and tendency to group in large clumps. While not a fish, they are an invasive aquatic species with a serious impact on the Great Lakes. Zebra mussels are filter feeders, straining algae out of the water. Where lake water was once green, supporting many smaller algae eaters that were in turn eaten by larger predators, the water is now clear, and many of these populations of fish are gone. Zebra mussels also tend to clog fresh water intake pipes around cities. They were brought in in the ballast water of ships from overseas, and ejected when the ballast was dumped.
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References
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