Wilderness Underfoot: Monsters in our waterways

StoryImage( ‘/Images/Story//Auto-img-112551156811410.jpg’, ”, ‘The common carp – Cyprinus caprio is a large member of the minnow family. This heavy-bodied fish grows to 7 pounds.’);

Carp are not well-liked in North America; these fish are considered destructive invaders on this side of the world

They stir up mud in lakes and rivers, and they hungrily consume native water plants, mussels, and invertebrates. They grow fast, breed fast, and drive native fish species to extinction. Their activities alter habitats, threatening birds and mammals that live at the water’s edge.

The invasive carp didn’t just show up here by accident. While some creatures have landed on the continent as stowaways in cargo, the carp was a hand-delivered pest, first brought here by European immigrants.

Today, carp are often regarded as unappealing by fishermen and gourmet cooks alike. But in the 1800s, they were considered an important food source in China and Europe. Immigrants to North America released the common carp, Cyprinus caprio, in rivers and streams, and the fish quickly established large populations. By 1885, the carp had been set loose in the Mississippi River. Because the Mississippi was so similar to the carp’s native rivers in China, the fish flourished. Today, the common carp is found in every state, with the exception of Alaska, and pound for pound it outweighs all the other fish in the Mississippi River.

While there isn’t much we can do now to control the common carp, fish and wildlife scientists are trying everything they can to control other species of carp that have arrived in North America more recently. The grass carp was released in the U.S. in the 1960s, and bighead, silver, and black carps arrived in the 1970s. These four species are a threat to Illinois rivers and, ultimately, the Great Lakes.

The most threatening is the bighead carp. This massive fish reaches 110 pounds, and it grows unusually fast. It feeds voraciously on tiny organisms and algae. And it migrates long distances during spawning season, so it doesn’t take long for this fish to spread through waterways and lakes.

The bighead carp is already well-established in the Mississippi and Illinois rivers. Fish and wildlife experts fear it will continue to migrate all the way up the Illinois River, crossing through the Chicago Sanitary and Ship Canal, and into Lake Michigan. Once there, it could wreak havoc on native fish species, damage the lake’s native habitats, and ruin fishing industries. And then it will move on to the other Great Lakes.

State and federal agencies have taken what may be the only measure possible to prevent the spread of carp into the Great Lakes. Near Romeoville, about 28 miles short of the Chicago Harbor, they have built an electrical barrier in the canal to repel the fish. Electrical cables charge the water, and experts hope this will repel the fish and keep them from crossing. So far, the carp have been found about 20 miles south of this barrier, but it appears that none has crossed the barrier.

From the Aug. 31-Sept. 6, 2005, issue

Enjoy The Rock River Times? Help spread the word!