Asian Carp, Aquatic Interlopers Threaten the Great Lakes

While the nation and the world morns the destruction of marine habitat and the deaths of an untold number of animals, birds, fish, and tiny organisms in the Gulf of Mexico, another battle is being waged, one in which people are desperately trying to find a way to eliminate one type of fish in an attempt to save many more.

The one fish species that is doing well these days is Asian Carp. Like many immigrants, the fish were brought to the United States to serve an economic purpose – in this case it was in the 1970’s, to clean algae from catfish farms. They escaped their captivity, however, and have flourished and spread throughout the Mississippi River and its tributaries, becoming a dangerous invasive species. Voracious eaters, the fish can grow to weigh up to 100 pounds.

There are two main types of Asia Carp. One is the Bighead Carp:

Source: AP File Photo

The other is Silver Carp:

AP Photo/The Star Tribune, Marlin Levison, File

This map shows where in the USA the Bighead Carp have been found:

Source: USGS

As the Asian Carp have moved upstream, there has been a growing effort to keep them out of the Great Lakes, the largest group of freshwater seas in the world, with more than 80,500 square miles of surface area.

Lake Superior:

If the Asian Carp reach the Lakes and breed well there (they prefer rivers), they could decimate the plankton which form the basis of the food chain for native fish species. The nightmare image that has people scared is that of the Great Lakes teeming with Asian Carp, and not much else.

Many strategies have been used to keep the fish out of the Great Lakes. They focus on a commercial canal system that connects the Mississippi River to Lake Michigan. A Treehugger article states, “For years the water in the canal was so polluted that it acted as a barrier; now that it has been cleaned up fish are swimming north. The only barrier is an experimental electric fence; it evidently causes great discomfort for the fish and they turn around and swim back.”

If the fence is down for maintenance or any other reason, poison has been used to keep the fish from passing – not a foolproof plan, and destructive to native species as well. When this was done in December of 2009, Asian Carp were among the species found, meaning that they had come withing 40 miles of the lake. The poisoning of the Little Calumet River in May, 2010 led to 100,000 pounds of fish being killed, but no Asian Carp were found.

The State of Michigan has sued Illinois to force the closing of the canals all together, and President Obama has stated his support for his home state in opposing he lawsuit.

This is a painful reminder that oil is not the only one of man’s activities that threaten to decimate entire ecosystems.

Our tendency to act before thinking may come back to hit us in the face – literally. When Asian Carp are startled by boat motors, they jump. Even the big ones jump.

Fisherman and water skiers beware.

UPDATE: On June 23, a 3 ft long Asian Carp was found in Lake Calumet, which is past the electronic fence and only 6 miles from Lake Michigan.

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