KANSAS CITY • The discovery of two juvenile black carp in a ditch connected to the Mississippi River in Missouri is the first, troubling sign that the invasive species is reproducing in the wild and becoming more of a threat to already endangered mollusks and some native fish, scientists say.
While adult black carp have been found sporadically in the Mississippi, the November discovery near Cape Girardeau of juvenile fish among the hundreds of fish caught showed the black carp population in the river is higher than scientists expected, Missouri Department of Conservation resource scientist Quinton Phelps said, and that there’s a “high probability” that more black carp were caught.
“Scientists really thought there were not enough adult black carp in the wild to find each other and reproduce,” Phelps said. “But what we found through this sampling is evidence there are enough to reproduce, and those young are surviving to a point where we are collecting them.”
Black carp can grow to 150 pounds and are the most efficient prey of mollusks in freshwater streams, according to Duane Chapman, a research fish biologist with the U.S. Geological Survey. That’s a problem because the Mississippi River basin has the most diverse mollusk population in the world, and three-fourths of the mussel species are threatened or endangered, he said.
But it’s not just about losing the mollusk species — there’s a domino effect. Lose the mollusks and there could be poorer water quality because some species clean impurities, as well as losing a food source for fish, muskrats, raccoons, otters and some birds, the conservation department said.
“A great number of species are in danger, species we’ve done a great deal of work to protect,” Chapman said. “Now we have this new threat coming in. Conceivably, one large fish in the wrong place could cause the extinction of an endangered species in one place in a year, before we even know it’s there.”
Black carp were brought to the U.S. in the 1970s to help fish farms fight snails, which carry parasites that are dangerous to several fish species. No native fish is as efficient and, at the time, farmers and the government didn’t want to use chemicals.
“Everyone was trying to help the environment, but it’s turned out to be a mistake, with potentially serious consequences,” Chapman said. It’s unclear how the species escaped from fish farms into the Mississippi River, he said, though some blame flooding.
Officials are asking the public to help stop the spread of black carp by not dumping their bait buckets indiscriminately and stocking ponds with fish from licensed vendors, Phelps said. And in some states along the Mississippi — including Missouri, Ohio, Illinois and Tennessee — any black carp caught in the wild can earn a $100 reward from Southern Illinois University, using money from the Illinois Department of Resources.
Because it’s a federal offense to carry a live black carp across state lines, anyone who finds one should kill it and try to bring it to authorities without freezing it, said Chapman, who is expecting to get funding this fall to develop a bait that targets black carp while not endangering other species or the public.
Another important step is being mindful of rules involving invasive species and the potential dangers of bringing them into the country, Phelps said.
“Everyone is up in arms about damage from species like feral hogs, whitetail deer, and other native terrestrial species,” he said. “The impact doesn’t seem to be as bad when the damage is under the water. But (black carp) is no different or less destructive than other invasive species’ interaction with native wildlife.”