Grass carp. Image: Eric Engbretson via Wikimedia
By Josh Bender
The Chicago River usually gets all the attention as a possible route for Asian carp to invade the Great Lakes.
But now one of the fish has been found at the opposite end of the Great Lakes system, about 750 miles east of Chicago in the St. Lawrence River, which drains the lakes to the ocean.
CBC News reports that two anglers caught a grass carp, one of four Asian carp species, in that river northeast of Montreal.
That could be bad news for the Great Lakes, some invasive species and environmental policy experts say. Elsewhere the voracious carp have chewed through vegetation, displaced the native species that rely on it and multiplied in great numbers. Environmental experts have long worried that if they get a toehold in the Great Lakes, Asian carp could significantly disrupt the native fishery there.
An electric barrier near Chicago is designed to keep the fish from migrating from the south through the Chicago River and Sanitary and Ship Canal and into Lake Michigan. Some environmental advocates have pushed to close that transportation canal to keep the fish out.
But there are other potential routes.
Last summer nine grass carp were caught near Toronto, CBC reported.
“If they are in the St. Lawrence River, they are in the Great Lakes,” said Marc Smith, policy director at the National Wildlife Federation’s Great Lakes Regional Center in Ann Arbor, Michigan.
The carp may have traveled from Lake Erie, where the fish and their eggs have been found, through Lake Ontario to the river, he said. “That should raise alarm for all the states around the Great Lakes.
The fish was between 15 and 30 years old, indicating it had been living in the river for quite some time, Smith said.
Varieties of Asian carp were introduced to the United States in the 1960s and 1970s, said Kevin Irons, aquatic nuisance species program manager at the Illinois Department of Natural Resources. Bighead and silver carp were brought in to clean commercial catfish ponds of excessive weed growth. The grass carp controlled shoreline vegetation.
The fish escaped to the wild when rain-swollen rivers breached their banks and flooded the ponds.
Almost immediately after their introduction, the carp began spreading, wreaking havoc where they went, Irons said.
The recent Canadian discovery prompted Quebec’s Forests, Wildlife and Parks Ministry to roll out a $1.7 million plan to fight the invasive species, CBC reported.