March 9, 2005

Aggressive aquatic species invading Great Lakes

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The non-native round goby has rapidly spread into the Great Lakes and has entered Cootes Paradise, a sensitive fish breeding ground in Lake Ontario.

Hamilton, ON - Foreign species, such as zebra mussels and carp, are invading the Great Lakes and changing the ecology of this vital ecosystem. A study from McMaster University published in the March issue of the Journal of Great Lakes Research suggests that for the round goby, a recently introduced fish species, their ability to wrest territory from native fish plays a key role in their dominance of the Great Lakes.

In the study, McMaster’s Sigal Balshine, an assistant professor of psychology, and her colleagues report that gobies win territory disputes against native logperch regardless of whether or not they were the original resident of the territory

“A territory owner, such as the logperch, is likely to fight hard to make sure it keeps its turf, but round gobies are extremely aggressive compared to the naturally occurring relatively peaceful logperch and easily take over contested shelters,” explains Balshine.

The researchers found that round goby abundance has increased dramatically throughout the Great Lakes basin since its arrival from the Black and Caspian Seas in 1990. Previous research has shown that round gobies eat eggs and young of various native species. Scientists believe that gobies have contributed to or caused the extinction of some native species in Lake Erie, the first lake to be invaded. “Obviously people are concerned about the effects on native species in the other lakes that gobies have now spread to,” says Balshine.

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