by Martha Leonard on Monday, Aug. 5, 2002 12:00 am
Illinois fish and game officials say Asian carp have worked their way up the Mississippi and Illinois rivers and are on the verge of entering a canal that feeds into Lake Michigan near Chicago.
The fish, which reproduce rapidly and can grow to 100 pounds, threaten native species because they eat food that young fish and other organisms need to survive.
"These are large fish in large numbers, and they consume a huge amount of microorganisms and plankton that would normally provide food for larval and small game fish and just about any other small organism," said Jim Rasmussen, a biologist with the U.S. Fish and Wildlife Service in Rock Island, Ill.
"They represent a significant threat. We've talked to commercial fishermen on the Missouri River who say these carp have driven them out of their fishing areas."
The culprits are two species of Asian carp — bighead and silver. Arkansas catfish farmers imported both species from China in the early 1970s to help clear their
ponds of plankton and vegetation.
They are believed to have escaped into rivers and streams during heavy flooding in 1992 and 1993.
Ultimately, they made it into the Mississippi River where they ate their way upstream to the Missouri and Illinois rivers just north of St. Louis.
"It's understood among all of us that these fish came out of Arkansas," Rasmussen said. "We even saw articles about it in Arkansas state fish and game publications in the '90s."
A 1997 publication of the Arkansas Agricultural Research Service notes that bighead were introduced into Arkansas from China in the early 1970s and that fish present in the Arkansas and Missis-sippi rivers are "probably escapees from one of the state's aquaculture facilities."
But Carole Engle, head of the fisheries center at the University of Arkansas at Pine Bluff, says Arkansas may be getting a bad rap.
"It's true that Arkansas was one of the first states to bring in Chinese carp, but Missouri and Alabama and other places did, too," she said. "There's no absolute proof of it, but there is a good chance they did come from here."
Escapees From Arkansas
While it's well-documented that Arkansas catfish farmers first introduced the bighead carp into the United States, government agencies themselves may be responsible in part for their escape into the nation's waterways.
"At one time all of the bighead carp in the U.S. were in hands of Arkansas Game and Fish officials," said Mike Freeze, a Lonoke County catfish farmer and member of the Arkansas Game and Fish Commission.
"The fish could have escaped from anyone's ponds — nobody knows really where they escaped from."
In 1978, catfish farmer Joe Hogan gave all of the bighead carp he had imported from China to the Arkansas Game and Fish Commission, which studied them for possible use in cleaning the state's rivers and streams.
They also were used in the late 1970s for an experiment on sewage treatment in Benton, conducted by the U.S. Environ-mental Protection Agency with help from the commission, Freeze said. The project involved putting concentrated numbers of bighead — 10,000 fish per acre — into a series of sewage treatment ponds, with the idea that they would dine on waste organisms and purify the water.
"The project worked well," Freeze said. "But we couldn't get cities interested in modifying their treatment systems to have six ponds in a row and using thousands of fish."
They also had a problem with what to do with the bigheads once they outlived their useful lives.
"You can't sell fish for food when they've spent their whole lives eating sewage," Freeze said.
Meanwhile, the carp present another hazard. Rasmussen says he has heard that leaping carp have caused bruises and even broken noses to humans. Some Fish and Game officials in Illinois have taken to carrying garbage can lids in their boats to ward off airborne carp.
"Our researchers have seen these fish jumping out of the water and hitting people in the head — it's just amazing," he said. "They're literally jumping into boats with people."
Engle says that may be true, but she is troubled that both species are being blamed. "The silver carp is the only one that displays such athleticism, not the bighead," she said.
An odd-looking creature, the bighead's eyes are located on the bottom half of its head, making it look like its head is on upside down.
"It's a bottom feeder, so its eyes are located where it can best see its food," Rasmussen said.
Researchers now say both species have been spotted at the mouth of the Kankakee River and other Illinois rivers, well north of St. Louis. The U.S. Fish & Wildlife Service reports that bighead carp are present in 19 states and that several have been captured as far north as the Missouri River in South Dakota.
Sightings have been reported in even more unlikely spots.
"One was seen on the Minnesota border [in the Mississippi River], a couple of bighead have been found in Lake Erie and one showed up in a fountain in downtown Toronto," Rasmussen said.
Chicago Mayor Richard Daley is so alarmed that last month he an-nounced that he may ask Congress for $700,000 in emergency funding to erect a second electrified barrier in the Chicago Sanitary and Ship Canal in Romeoville, 40 miles from Chicago.
One $2.2 million barrier already exists there. It was built to keep another exotic species, the round goby, out of lake Michigan.
"But it's never been tested on carp, and now they need two," Rasmussen said. "If you don't stop them cold, they will keep spawning and get all the way up to Canada."
Engle says she doesn't understand what all the fuss is about.
"I've heard all this talk at meetings in the last couple of years about the bighead taking over," she said. "But every time I ask where the population estimates are, they can't answer. I want to know who is out sampling to get the numbers."
Besides, she said, bighead are easy to catch and easily could be eliminated just by catching and destroying them or selling them for food.
Some Arkansas fish farmers raise bigheads along with catfish. Out of the 69,000 acres of water devoted to aquaculture in Arkansas, about 4,000 acres of earthen ponds are used to "polyculture" the catfish and bighead carp.
Carp is considered tasty in some European and Asian cultures, but it is generally not eaten by North Americans. The fish are trucked live to markets in cities where a large Asian population prefers to keep the fish alive until immediately before cooking.
"We sell them to distributors who transport them to New York, Chicago and Toronto," said Joey Lowery, a Jackson County catfish farmer.
The carp grow quickly even in captivity and are cheap to feed. They eat the plankton that naturally flourish in catfish ponds.
"It's unbelievable how they grow, even in pond culture," Lowery said. "At the optimum growing time, they can put on 2-3 pounds a month."
The optimum selling size for bigheads is 8-12 pounds.
Lowery has been raising bigheads for about five years. The price he gets fluctuates with demand.
"Right now we're getting about 60 cents a pound for them, which is pretty good," he said. "I've seen it as low as 25 cents and as high as 65 cents. When bighead first came into the market it brought a pretty big price."
Lowery expects to see some cooling of demand for bighead, which may be due to Asian youth being less finicky about their fish.
"The older generation won't eat anything but fresh fish," he said. "But I think a lot of the younger generation is happy with frozen fish, and that is giving the foreign imports an opportunity to move into the market."
In the early 1990s, about the same time bigheads were escaping into the Mississippi River, researchers tried to find a broader market for bighead carp.
Engle, along with U.S. Depart-ment of Agriculture food technologist Donald Freeman, conducted a consumer taste test study for canned bighead carp.
The fish has lots of tiny bones and is best eaten as a canned product. Canning softens the bones, as it does for salmon.
"We set up an operation in Fayet-teville where the fish were processed and canned, just like a tuna pack," Engle said. "People reacted very favorably in a statewide test."
Six of 10 study participants said the canned bighead carp tasted better than tuna. "It really came out on par with albacore tuna, and you can do anything with it that you can with albacore," she said.
The problem with the bighead turned out to be not its taste but its, well, big head.
"Because it has such a big head, the dress-out [or usable product] on this fish is not very good," Engle said.
Another problem was catfish prices were very low when Engle started the bighead studies, then the price went back up and interest in the canning idea dwindled.
"It tasted like albacore tuna, but it turned out that the price was going to be about the same as albacore, and that's a high-dollar tuna," Freeman said. "We didn't think people would pay that for canned carp."
The cannery could afford to pay farmers only 10-20 cents a pound, and farmers say they have to get at least 40 cents to cover their costs.
"Of course, if you're a commercial fisherman out in the river your costs are going to be a lot lower," Engle said, referring to the idea of commercial fishing for nuisance bigheads in the Mississippi as a means of controlling their numbers.
Rasmussen says he and other researchers in the Mississippi River Basin are open to any ideas that will stop the spread of bigheads.
"Canning is one way I guess, but you still have to deal with people's natural aversion to eating a delicacy out of a can that's named 'carp something-or-other.'"
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