Commercial netters working to reduce invasive carp on the Illinois River broke their own records twice in the span of a few days, catching a 90-pound carp before capturing a 109-pound carp near Morris the very next day.
Jason DeBoer, an ecologist with the Illinois Natural History Survey, said he’s certain this is the largest two fish his group has ever caught and a quick Google search shows him that it may be the state record for big-head carps. It may also be the largest in most of the Mississippi River Valley states.
DeBoer said the fish grow that big because they’re indeterminate growers, meaning they grow their entire life. That growth slows once they reach sexual maturity, but fish keep growing for their entire lives.
“From the fish’s point of view, the larger you can be for a female like that, the more eggs you can grow every year and the greater your chances of successfully passing on your genes,” DeBoar said. “The reason a fish that big is a problem for us is that it’s an invasive carp that makes a million or 2 million babies every year.”
Not all of these babies survive very long, but DeBoer said about 1% to 2% of them do and 2% of two million is still a lot of baby carp swimming around. By removing the 109-pound carp and the 90-pound carp, the netters have ensured these two large fish will no longer create any more of the invasive species.
DeBoer said biologists work along with the commercial netters to count the fish they get in the boat, whether it’s native fish or invasive fish caught. This helps biologists track the weight of the invasive carp that get removed, and it gives them a way to monitor native fish populations to see if they’re responding positively, negatively or not at all to removal efforts.
These two large fish are big-headed carp, not silver carp. DeBoer said these are both invasive species, but the silver carp are the ones people think of first because they see them jumping into and around boats in the water. Big heads, DeBoer said, do not have the thrust in their tail.
“Every time we see a giant carp like that or, we call it the popcorn machine, we see silver carp exploding or jumping thousands of fish all at the same time, my 12-year-old thinks that’s one of the coolest things in the world to see,” DeBoer said. “But the 44-year-old fisheries biologist in me understands the ecological devastation that many invasive fish or a single invasive fish can cause.”
Whether or not the problem of these invasive species ever goes away, DeBoer isn’t sure. He said he can look through rose-colored glasses and say it’ll go away, but he doesn’t know that it will.
He said there are many efforts to understand, slow down and stop the invasion. This includes the Brandon Road Lock and Dam project near Rockdale and the electric barriers keeping the carp out of the Great Lakes. DeBoer said these commercial netting efforts are the next best line of defense to reduce the number of fish in the upper river.
“Another arrow in the quiver is rebranding that the Illinois Department of Resources was part of last year trying to convince people that silver carp are actually a viable food fish,” DeBoer said. “They are the most intensively aqua-cultured fish on the planet where they’re native in eastern and southeastern Asia. The people there cannot get enough of them, and they can’t grow enough to meet demand.”
Why don’t these fish catch on as food in America as well?
DeBoer said it’s because Americans don’t like bones in their fish.
“Chicken wings, ribs, pork, we’ll eat those until our fingers bleed,” DeBoer said. “But if you put bones in our fish, we don’t want anything to do with it.”
DeBoer said these fish are healthy to eat and given there are now so many of them, they can be wild-caught and wild-sourced. To prove it, he said they have a large fish fry serving silver carp to show technicians that it’s a viable, tasty food source that will volunteer itself by jumping right in the boat.
Another thing DeBoer wants to reiterate is that these fish are not dangerous to people as far as river-use goes. These carp aren’t going to eat people or children: They eat plankton, so they won’t even nibble on toes.