SPRINGFIELD - Asian carp continue to terrorize Illinois rivers and endanger fish native to the state, but some observers say they might at least be getting skinnier.

The population of the invasive fish has boomed in recent years, leading industry fishermen along the Illinois and Mississippi Rivers to dread the carp as they perhaps squeeze native fish like catfish out of the picture.

And they've become famous from videos and tales of the fish jumping high from the water when stirred up by boat motors. Sometimes, they've hit and injured people.

But now it appears the Asian carp could be doing themselves damage simply because of their sheer numbers.

Scientists have noticed the large fish are growing a little less large. It's most noticeable in the Missouri River, but the trend can be seen in the Mississippi and Illinois, too.

"There's less resources than mouths out there," said Kevin Irons, an ecologist with the Illinois Natural History Survey.

Skinnier, weaker fish might mean the carp can't reproduce as fast. And that could mean waterways are less clogged with the fish.

"It could give our native species a reprieve," Irons said.

The Asian carp's invasion of the Midwest has been a significant issue in recent years as officials try to keep the fish from swimming up the Illinois River and into Lake Michigan.

An electric barrier in the river is helping with that, but people who make their living trying to pull native fish out of the river for sale want to see the carp wiped out.

They don't hide their animosity toward the fish.

"It's too bad they don't all starve out and die, but they're not going to," said Kirby Marsden, president of the Illinois Commercial Fishing Association.

Lawmakers this year have approved a plan that would let the state work with Southern Illinois University to figure out how to start eliminating the fish, or at least curb its growth.

But, that program would have to be paid for, which is no guarantee given the state's financial crisis.

The legislation is House Bill 872.

Video of the jumping fish can be found at:

http://www.youtube.com/watch?v=JfJoQQwNgUU