Flying Fish: Asian carp menace spreads
MILLTOWN -- A fish out of water -- and then another and another.
As Cari-Ann Hayer made her way down a narrow channel of the James River in a small aluminum boat, numerous Asian carp broke the surface of the murky water behind her. The aerial display reached heights of more than 6 feet at times, proving why Asian carp are nicknamed "flying fish."
One landed directly in her lap, and she slowed the boat down and casually threw it into a nearby cooler.
"That's one less we have to catch," she said.
Hayer, a South Dakota State University doctoral student, began researching Asian carp in 2010, studying their effects on South Dakota waters by collecting samples from the tributaries of the Missouri River.
She was on the James River on Tuesday with a team of two other researchers collecting samples of the nuisance fish.
In the close to one-mile stretch of the James River north from Milltown that Hayer traveled in her boat, eight silver carp jumped directly in. Many others banged against the aluminum hull. The motor from the boat is said to agitate the fish, causing them to jump when they come in close proximity.
"I've been told they don't jump like this in Asia," she said. "But I have no explanation as to why they would only do it here."
Asian carp were first spotted in South Dakota about 10 years ago when they started jumping below Gavins Point Dam on the Missouri River. They now inhabit the entire stretch of the James River in South Dakota as well as the Big Sioux and East and West Vermillion rivers. The invasive fish can grow to weights of more than 25 pounds and are divided into four species: the silver carp, which are most prevalent and are also the species that jump out of the water, the bighead carp, the grass carp, and the black carp.
No population estimate is available for South Dakota, but numbers are growing exponentially in places like this part of the James River.
The fish were originally brought to the United States in the 1970s to be used to clean the ponds in catfish farms in the South. It is believed that in 1974, some of the carp escaped from the ponds in Alabama during a time of heavy flooding. From there, the fish slowly crept northward by way of the Mississippi River and Missouri River. They traveled up the James by way of the Missouri at the two rivers' confluence near Yankton.
Asian carp are not believed to be above Gavins Point Dam in the Missouri River, because the dam provides an effective barrier against further invasion of the fish. The Jamestown Dam in North Dakota provides a similar barrier on the James River.
Hayer and her team use an electrode that sends a small current through the water causing the silver carp to jump.
When they turn the machine on, the water is aflutter with constant splashes as more than a hundred silver carp make their way in and out of the muddy water. One researcher, Jessica Howell, used a net to grab them out of the air as another research slowly drove the boat through the river channel.
Hayer said it's almost as effective to drive slowly with a boat motor and let the fish jump directly into the boat.
Hayer and her team measure and weigh each fish. The intestines of about 25 fish from a specific size range are removed immediately and put on ice to stop digestion. The rest of the fish are taken back to the lab for further analysis and to determine their age.
Last year, age zeroes, or newly born silver carp, were found in the James River for the first time. That could indicate the invasive species is using the river to spawn and not just migrate.
So far this year, research has been a bit more positive. The team has only been catching fish in the two- to three-year age range, and few fish born last year have been caught.
"That is the one bright side we have found so far from the research," Hayer said. "We are not really sure why this is. They could have moved out of the area, but we are hoping that they didn't have a good spawning year and there aren't very many of them around."
Hayer said too little is known about the fish to understand how times of heavy flooding, like in 2011, and times of drought, like this year, might affect the Asian carp population.
"The silver carp is generally found in rivers that are deeper than this area and ones with a larger watershed, but as you can see, that isn't really stopping them in this part of the James," Hayer said. "That's what invasive species do: They adapt and they find new ways to survive."
"People always ask if they can survive our harsh winters, and the answer is absolutely," she said. "These are hearty fish that are highly motivated to adapt and spread."
She is hoping to better understand the silver carp's place in the food web in hopes of learning what effect they may have on river systems.
"The average fisherman should be very concerned about them, because they could affect your walleye," she said.
'Right over the top'
Because the Asian carp is considered to be at the bottom of the food web, it can conceivably affect every species above it.
Asian carp can grow to such huge numbers in an area that they decimate zoo-plankton and algae populations in a river. That would in turn kill smaller fish that also feed on those plants. The larger, predatory fish that feed on the smaller fish would suffer as well.
Sheer over-population of a species of fish, like is common with the silver carp, can also create habitats that are not sustainable for other fish because they are too tightly packed.
"When you get to many Asian carp in an area, the other fish move to try and find a new place to live without as much competition," Hayer said, pointing out that other species of fish should have come to the surface when her boat's electrode was turned on, but few did.
Collapsing the food web of a river isn't the only problem these nuisance fish can bring. Their jumping displays could affect many boaters as they spring out of the water and crash into people and objects, possibly causing injury.
About 20 low-head dams span the James River from the Missouri River confluence to Jamestown Dam in North Dakota.
"Obviously, those dams aren't keeping them in one area." Hayer said. "You can see how high they can jump -- they can just go right over the top."
Silver carp were netted as far north on the James River at Jamestown last year, though according to Hayer, lower water levels in 2012 have forced most of them downstream back into South Dakota.
The South Dakota Department of Game, Fish and Parks implemented a no bait-catching rule on the James River in hopes of preventing accidental spreading of Asian carp to other waters in South Dakota. Because small Asian carp look very similar to gizzard shad, a popular baitfish, no one may take baitfish from waters that are known to have Asian carp. The rule was also implemented on the Firesteel Creek below Lake Mitchell this year.
Hayer believes finding and studying spawning of the nuisance fish will eventually lead to a way to control the species.
"If we can figure out where they're spawning and understand those habits, then you can effectively control the species by cutting that area of and not allowing them to spread," she said.
Once Asian carp implant into an area, they are difficult to eradicate.
"That is really the million dollar question: How do you get rid of them once they are there?" said South Dakota Game Fish and Parks Chief of Aquatic Resources John Lott.
Fisheries officials in Chicago are beginning to use electric currents in the water that act as barriers in hopes of stopping the Asian carp from reaching the Great Lakes through Chicago shipping channels.
Lott said a "biobullet" is being developed to fight the fish, which would act as a toxin on the carp but would not harm other fish or plants. But that research is still in its infancy.
"Right now we need to do everything we can to stop the spread of these fish, and then we can start to work on ways to get rid of them," Lott said.
Asian carp are considered an invasive species and there is no limit on the number of them that can be caught. If anglers do catch Asian carp, the fish must be dead to be transported.
Commercial fishing of Asian carp is also a possibility, because the fish are in high demand in China, but Lott said U.S. processing facilities are not set up to prepare the carp after they are caught.
In Illinois, where the Asian carp problem has reached epic proportions, officials are trying to essentially eat the problem away.
The Illinois Department of Natural Resources has begun to partner with Feeding Illinois to catch tons of fish and process them into fish sticks and donate them to the St. Louis Area Food Bank. Asian carp is a good source of protein, said Tracy Smith, Feeding Illinois' director, and other sources are getting expensive. The hope is that food pantries will catch on to this cheap and readily available source of meat, and that will create enough interest for supermarkets to start selling them.
In South Dakota, no such program is in place with the use of Asian carp, but Feeding South Dakota's Jim Dawson said if the resource were available, he would gladly use it. The group has used farm-raised carp packaged as minced fish before, but never wild-caught Asian carp.
Dawson said it would be difficult to utilize Asian carp as a resource until commercial fishing and processing is put in place.
"I think it would be hard to do it in South Dakota, because we have no way to process the fish into meat. But if there was some way to do it, we would gladly use it, because it is a protein-rich food source."