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Carp
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, or cloudiness in the water, which can lead to declines in waterfowl and important native fish species. The common carp was introduced by unintentional release in 1879. |
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Goby
The goby is a bottom-dwelling fish that has great potential for causing impacts on Great Lakes fisheries. Originally the round goby and the tubenose goby were introduced into the St. Claire River in 1990, probably via contaminated ballast water of transoceanic ships.
Round goby are thriving in the Great Lakes Basin because they are aggressive, voracious feeders which can forage in total darkness. The round goby takes over prime spawning sites traditionally used by native species, competing with native fish for habitat and changing the balance of the ecosystem. The round goby is already causing problems for other bottom-dwelling Great Lakes native fish like mottled sculpin, logperch and darters. Goby can also survive in degraded water conditions, and spawn more often and over a longer period than native fish. Unfortunately, they have shown a rapid range of expansion through the Great Lakes. |
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Sea Lamprey
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 in 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. |
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White Perch
White perch are native to Atlantic coastal regions and invaded the Great Lakes through the Erie and Welland canals in 1950. White perch are prolific competitors of native fish species and are believed to have the potential to cause a decline in the Great Lakes walleye population. |
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Ruffe
The ruffe, a small spiny perch capable of explosive population growth, is one of the latest foreign arrivals threatening the Great Lakes fishery. Native to lakes and rivers in Eurasia, the ruffe was introduced to Duluth Harbor on Lake Superior in 1986 via ballast water of an ocean going vessel.
The ruffe competes with native fish for food and habitat. Its ability to displace other species in newly invaded areas is due to its high reproductive rate, its feeding efficiency across a wide range of environmental conditions, and characteristics that may discourage would-be predators such as walleye and pike.
Ruffe are primarily bottom feeders, preferring dark environments where they can hide from predators. They rarely grow bigger than 5 inches, although the sharp spines on their gill covers, dorsal and anal fins make them difficult for larger fish to eat. |
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Zebra Mussels
Zebra mussels are small, fingernail-sized mussels native to the Caspian Sea region of Asia. They are believed to have been transported to the Great Lakes via ballast water from transoceanic vessels. The ballast water, taken on in a freshwater European port was subsequently discharged into Lake St. Clair, near Detroit, where the mussel was discovered in 1988. Since that time, they have spread rapidly to all of the Great Lakes and waterways in many states. |
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Quagga Mussels
Quagga mussels are close cousins of zebra mussels and have outnumbered zebra mussels in several areas of the Great Lakes. They are slightly smaller than zebra mussels and have rounder shells with dark concentric rings.
Quagga mussels appear to tolerate a wider range of extremes in temperature and water depth than the zebra mussel and spawn at colder temperatures. Quagga mussels are able to remove large amounts of phytoplankton and suspended particulates from lakes and streams; this ability decreases food sources for zooplankton and bottom-dwelling organisms such as Diporeia—thereby altering the delicate balance of the aquatic food web. They also clog water structures such as pipes and screens, which reduces pumping capabilities for water treatment and power plants—creating huge problems for industries and communities burdened with removal and clean-up costs. Recreational activities and industries are also negatively impacted by quagga mussels when docks, buoys, boats, beaches, and breakwalls are heavily colonized by the species. |
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