On Outdoors: Not much to go on from Asian carp studies

By Jim Hagerty
Staff Writer

While the presence of bighead Asian carp in the Illinois River continues to be widely experienced, wildlife officials have yet to announce the impact the species has had on native fish.

Because what is now being called an invasion is recent, biologists are taking their time to assess studies. Meantime, boaters are being physically bombarded by bigheads as they fish. Spooked by motors, Asian carp will leap out of the river and hit whatever is in their path. It is not uncommon for a ride down the Illinois to include a whack in the head by a soaring 10-pounder.

Most who know the Illinois River and Asian carp continue to notice the population of the invasive species seems to have doubled—even tripled—in some spots. Still, the focus remains on keeping the fish out of the Great Lakes and the legal battle to close down a vital Chicago shipping canal.

In June, a 20-pound Asian carp was caught in Lake Calumet, 6 miles beyond an electric barrier. The catch has heightened political tension throughout the Great Lakes region, leaving expensive options on the table.

Officials predict that if Asian carp find their way into the Great Lakes in large numbers, the $7 billion commercial and sport fishing industries could be devastated within a few years. Closing the canal would deliver an equally devastating blow to the shipping and farming sector.

Bighead Asian carp are voracious eaters and threaten the ecosystems of native fish, robbing them of nutrients.

A 2007-2008 study in the lower Illinois River produced stats that some considered staggering. Carp densities of about 19,500 pounds per mile have officials scratching their heads. Documenting its negative impact, however, isn’t mathematically possible until the species is allowed more time to thrive.

“It’s still kind of hard to tell exactly what the impact is or what the final impact is going to be,” said Ken Clodfelter, fisheries biologist at Hennepin Canal Parkway.

In similar situations, it was decades before biological trends could be established, a fact officials are facing with caution.

Researchers say the patterns of non-invasive fish need to be followed to determine how Asian carp are affecting the natural ecosystem. Food web disruptions and population declines will eventually tell the story.

Outdoors news and photos can be sent directly to Jim Hagerty at jim.hagerty@rockrivertimes.com. Glossies and hard-copy press kits can be mailed or delivered to The Rock River Times’ office at 128 N. Church St., Rockford, IL 61101. Jim can be reached at (815) 964-9767.

From the Aug. 4-10, 2010 issue

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