Hulking invasive fish with voracious appetites are striking at the threshold of the Great Lakes as U.S. and Canadian officials scramble to keep them out.
This past June, a nearly metre-long bighead carp was caught by commercial fishermen in Lake Calumet in Illinois, beyond an electric barrier system meant to bar the fish from Lake Michigan and the other Great Lakes. Tests released in August suggest the six-year-old fish had lived most of its life in Great Lakes waters.
The bighead carp, native to Asia, can reach a mass of 27 kilograms — similar to that of an average eight-year-old child. The silver carp, a related Asian fish, can reach a maximum size of almost double that.
Both fish are voracious feeders that vacuum up huge amounts of plankton, the tiny organisms that form the foundation of the Great Lakes food chain. This means native fish such as lake trout and walleye that feed on plankton as small fry could starve.
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