Another Invader Thwarted… for now
Grass Carp Threatens Great Lakes Waters
Asian carp have made it up the Mississippi almost to the intersection of Chicago Sanitary and Ship Canal and the Chicago River. Catfish farmers who wanted to keep their ponds free of algae and other detritus imported two species in the 1970’s and they escaped during the floods twenty years later. These high-jumping giants have already crowded native fish out of the Illinois and Missouri Rivers. Now they are threatening the Great Lakes.
The Great Lakes are ideal environments, very similar to the water conditions in China where the fish are from. They are huge. They grow quickly up to four feet long and 100 pounds. They also leap. When startled some species can hurl themselves eight to ten feet above the water and there have been many instances of boaters injured in airborne collisions. A greater harm, of course, would be the damage to existing fish populations in the Lakes and rivers. A permanent electric barrier should be fired up near Chicago very soon and it is expected to keep the carp in the river.
A temporary barrier has been in place for some time. It sends out a current of one volt per cubic inch of water. The new, permanent electric “wall” can send out four times that and is expected to block the fish even in the turbulence that follows barges and other larger craft. Cruising craft in the area will be encouraged to keep moving through the barrier and not linger.
Unfortunately, some bighead and grass carp have already been captured on the Canadian side of the lakes. They probably came from the live carp market. As yet, no known populations have been established. Too bad they don’t eat lamprey eels and zebra mussels!