MOUNT VERNON — By now, most people have heard that the Asian carp are coming. The true reality is that they are already here — in the United States that is — and they are causing havoc.
Asian carp are originally from Eastern Russia and China, but are related to the common carp found in the United States. The Asian carp family is essentially made up of several different species.
“They are mostly in rivers in Asia,” said Ohio Division of Wildlife program specialist John Navarro. “There are actually four different species, but only one or two have made the headlines though. The big ones are the silver carp and the black carp. Silver carp are the ones that are the jumpers, and they’ve been in a lot of news media. There are also the big head (carp) and the grass carp. They are all bad for various reasons.”
These fish, which can reproduce quickly, were originally introduced to America in the 1970s, and since that time, have multiplied exponentially.
“These fish were brought over for use in aquaculture down south,” said Navarro. “The black carp eat snails, which are a host for some parasites. Catfish farmers like those in there to knock the snails down. Flooding helped them escape. It started with best intentions, but some severe flooding flooded those aquaculture facilities and of course, those fish aren’t going to stay put. They got out and they’ve been moving north ever since.”
Asian carp are considered an invasive species because they are not native to this continent. Most species would struggle to survive as conditions change. Asian carp, however, have shown an ability to adapt to their environments.
“Invasives are so successful because they can adapt to different conditions,” said Navarro. “There is no evidence that the cold bothers them; it hasn’t slowed them down.
“Both the bighead and the silver (carp) are knocking at the door of Lake Michigan. There is actually evidence that they made it past the barrier.”
The barrier that Navarro referred to is an electric fish barrier, which was constructed in 2002 by the U.S. Army Corps of Engineers in the Chicago Sanitary and Ship Canal. The canal connects the Great Lakes and the Mississippi River. The initial barrier was considered ineffective and a second, permanent barrier was built in 2004.
The barrier is the only thing separating the carp from the Great Lakes. Should they make it through in numbers, the carp could destroy the ecological balance, and with it, the fishing industry.
“If and when they get into the Great Lakes, it is going to harm the food chain,” said Navarro. “The silver and bighead carps are filter feeders, and they feed on the phytoplankton young native fish use as a food source. They’ve had evidence of that in the Mississippi River. Over 95 percent of the biomass, which is the weight of the fish being caught, are Asian carp. They just overwhelm the system.”
Over the last few years, many efforts have been made to slow the Asian carps’ growth, but so far, all efforts have been unsuccessful. That’s where the problem comes in.
“There is no way to get rid of them,” Navarro said. “Once they are in, you’re done. If they are able to establish a reproducing population in Lake Michigan, it’s over. They’ll end up in Lake Erie and they’ll love Lake Erie. They might not like Lake Superior, Huron or Michigan as much as Lake Erie because Lake Erie is so productive. It will be just a matter of time if they make it into the Great Lakes.”
Several states joined in filing an injunction request, seeking the immediate closure of the Chicago Sanitary and Ship Canal. On Monday, the U.S. Supreme Court rejected the injunction request, which has wildlife officials in all of the Great Lake states scrambling. Ohio stands to lose possibly the most if Asian carp make Lake Erie their home.
“We just don’t know the total ramifications,” said Navarro. “Every time a new invasive comes in, you’re just wondering if that’s going to be the one that tips the balance and crashes the system. The zebra mussels have already changed the ecology of the lake, and you just don’t know if Asian carp could be the death blow. They could crash the whole system, and if that happens, you’re done. Basically, they’ve just ruined a multi-billion dollar industry.
“The Great Lakes are such a complicated system, I don’t know how you would project the impact they could have. The only thing we can say is that there is a real good possibility that it is going to be really bad. ... They were first discovered in the lower Mississippi about 10 years ago, and they are already knocking on the Great Lakes. That’s a heck of a trip to make in numbers.
“The other thing, aside from the ecological disaster that could happen, is human safety,” added Navarro. “There are records of the silver carp knocking jet skiers off their jet skis and hitting boaters. The noise of the prop will get them to start jumping, and they will fly into boats and hit people. It is all funny when they hit people in the family jewels, but when they hit you in the head and chest, they can do some damage, so it is really not very funny.”
Asian carp are also headed toward Ohio by way of the Ohio River. They are not, however, making as quick of progress in their migration.
“We’ve had reports of them (in the Ohio River), but they really haven’t made it in numbers to Ohio yet,” said Navarro. “They are still downstream. The lock and dam structures are slowing them down. It’s not like they have a free reign of the Ohio River, but eventually, they will end up here and, probably, into some of our major tributaries — the Scioto, Great Miami, the Muskingum. ... Individual (fish) have been caught in our portion of the Ohio River, but it is just one here and one there. We don’t have the massive numbers like they have in the Mississippi.”
Navarro expects Asian carp to eventually reach Ohio’s rivers and streams, though they may stay in the larger waters.
“As the rivers get smaller and smaller, the carp are less adaptive to those situations,” Navarro said. “I know they like the larger rivers because there is more food and more room to roam. These things like to move around and can grow quite large. On average, they are about 10 pounds, but they can get very large (80 to 100 pounds).”
The Division of Wildlife is currently not taking an active role in controlling the Asian carp. It is relying on the efforts of other states, but that could change.
“We’re depending on the Army Corp (of Engineers) to operate the electric barrier and keep them out of the that end of the Great Lakes,” said Navarro. “We’ve obligated money to them to help with the rotenone effort they had. The electric barrier has to be shut down for maintenance every year, and the Asian carp were backed up behind that. The fear was when they shut it down for a couple of days, those carp would make a run for the lake, so they put a fish toxin called rotenone into a 5-mile stretch of the canal system to kill them off while the barrier was down.”
Recent study results found Asian carp DNA in the waters of Lake Michigan, which suggests the fish could have gotten through the barrier one way or another. Results from the rotenone effort were inconclusive as only one carp was found among the 90 tons of dead fish.
“They possibly could have got through if they could have survived the rotenone treatment,” said Navarro. “The other possibility, which is kind of scary, is that the electric barrier is not as good as everybody is advertising it to be.”
One thing is clear when it comes to Asian carp: There is much uncertainty to their future and that of the Great Lakes. Officials, however, would rather be safe than sorry.
“Anything is possible,” Navarro said. “I really hate to paint gloom and doom, but to sit here and say, ‘It is not that big a deal,’ would be doing it a disservice. It very well could be really bad. ... The big concern is that they reproduce in such large numbers it will affect the food chain. They’re filter feeders, so they basically clean the water up, which young walleye and young yellow perch are using as a food source. If you have a bunch of these carp cleaning the water up, that leaves less food for the native fish to use.”