Holy Carp!

June 19, 2007 — -- These fish may seem thrilled as they leap into the air, but local scientists are not exactly jumping for joy at the presence of Asian carp in the Illinois River.

The fish can weigh as much as 100 pounds, are known for their ravenous appetites and immense size, and behave like playground bullies.

They steal food from other fish, tear up the river bed and shoreline, destroy the ecological balance of the river, and in some cases, harm boaters.

Fishery biologist Eric Leis said while it's "amazing" to see them jump, it comes at a cost. "They disrupt the ecosystem. They basically eat all the food — the bottom of our food pyramid for all our native fish."

Not only do they jump out of the water, but they hurl themselves into passing motor boats, according to Leis, apparently "excited by the motor and waves from the boat.

"It could turn a leisurely day of fishing into an extreme sport. They can get up to 80 pounds and fly 8 feet into the air, causing, as you can imagine, injury to whoever is in their path," he said. (Click on the video in the right side of this page, shot by ABC News' Chicago bureau, and see just how invasive this species has become.)

Originally imported from China as pond cleaners, Asian carp have made their way up the Missouri River from Arkansas over the past decade, devouring plankton and devastating the environment in their wake.

Now, these ferocious fish are approximately 50 miles from Lake Michigan and threaten to invade, an event that could prove disastrous for both the native species and the ecological balance of the lake.

Although researchers cannot predict how long it will take the carp to reach the Great Lakes, local scientists work day and night on ways to block these jumpers from taking over the rest of the river.

Over the past few years, the Illinois Department of Natural Resources has tried a number of different methods for eradicating the state's carp crisis — everything from putting chemicals in the water to holding an annual Redneck Fishing Tournament, neither of which have seemed to put a dent in the problem.