The trouble is that carp don’t have any idea of when enough is enough. They keep eating long after they’ve eaten the weeds they were brought in to control. Often the surface weeds aren’t their first choice, and it’s only after wiping out most of the important native aquatic plants that they get around to eating the things people are trying to get rid of.
This has obvious consequences for the rest of the ecosystem. Removing native plants means they’re not available as a food source for other aquatic herbivores. Also, the plants are no longer providing cover for smaller fish and invertebrates, increasing the amount of predation on them by other species and gradually reducing their numbers. These changes produce a domino effect that creates other ecological problems.
Once the easy food is gone, the carp need to root around for more. Their constant search stirs up sediment that clouds the water. This decreases the amount of light reaching the bottom and further impedes growth of the aquatic plants necessary for the healthy functioning of the pond ecosystem.
Unfortunately, human beings tend to be more concerned with the aesthetics of nature than with its health. A surface covered with scum may not be the best thing for a pond, but dumping a bunch of heavyweight fish that can grow up to fifty pounds will eventually make things worse. State governments have recognized this, and in most places it’s now illegal to introduce viable — that is, able to reproduce — grass carp into the wild.
Nonviable carp, on the other hand, are sometimes stocked. Grass carp can be made to be triploid through artificial means. A triploid grass carp has an extra set of chromosomes that cause it to be sterile. This condition is usually induced by spinning the eggs in a centrifuge very quickly and then stopping; the rapid change in pressure naturally results in the extra chromosomes. Triploid carp are considered safer for weed control because they can’t reproduce and get out of control.
Although they can’t reproduce, they can still wreak havoc for years on the water system they’ve been introduced into. And even when triploid carp are purchased in good faith, there’s no guarantee that they are, in fact, what they’re advertised to be.
Carp breeders are known for being meticulous about ensuring that all the fish they sell are unable to breed. Many of them test every single carp before making a sale. Not every egg turns out triploid, and success rates for a batch range from eighty to one hundred percent. There’s decent government oversight of the breeders, and they’re seldom a problem. The middlemen who buy from the breeders, however, are somewhat of a mixed bag.
Carp expert Duane Chapman, of the United States Geological Survey, let me in on a little secret about triploid grass carp: They aren’t always triploid. The value of a standard grass carp is much lower on the market than that of a triploid grass carp. An unethical middleman may buy a certain quantity of certified triploid grass carp and a larger amount of standard grass carp. In the event of an inspection, he presents the certification for the triploids. In that way, he sells the standard carp fraudulently as triploid. The total sales figures are obscured, and it’s unlikely the transaction will be questioned by the authorities. Even if fraud is detected, it can be very difficult to build a case.
As you can see, stocking what are believed to be sterile, triploid grass carp isn’t guaranteed. Viable carp are being introduced to the wild via the triploid exception. If there’s any route by which the carp can escape from a pond into moving water, which is what they need in order to spawn, trouble is around the corner. Even when a drainage stream looks too small for the carp to escape through, this can change rapidly with a heavy rain.
Even when stocked carp are definitely triploid and don’t pose a risk of escaping and breeding in the wild, they still wreak havoc on the pond ecosystem they’re introduced into. The fish are often stocked when they’re about twelve inches long. Say that twenty carp are stocked. A year later, the weeds are gone and the carp might be twenty inches long. But they keep getting bigger. In another year those twenty carp might be thirty inches long. They’re having a bigger effect on the habitat every year. If the desired effect (weed removal) was already achieved, then, rationally, the number of carp should be reduced. There’s no need to keep a thousand pounds of carp rooting around in the pond if half that biomass was doing the job the year before.
I began experimenting with various fishing methods for the grass carp in my family pond. At first I tried hooks baited with corn, which many people swear by. The fish weren’t the slightest bit interested. Even when I chummed an area with it and came back the next day, the corn was untouched. Next I tried ambushing them with my cast net, ready to throw it over a fish as soon as it came within range. Carp are just too wary and pay too much attention to what’s happening above the surface for that to work. They were always out of the path of the net by the time it hit the water.
Maybe snagging them would work. In warm weather, carp like to bask at the surface. While bass fishing, I discovered that I could cast over a fish’s back from far away and it wouldn’t react to either the lure or the hook sliding over it. Now, I bought the biggest treble hook I could find and tied it onto an eighteen-pound test line on my heavy surf rod with a weight under it. Just my luck: the temperature dropped right when I did this and the carp stopped basking.
I was running out of ideas on how to clear out these carp when I drove to Connecticut to try the shore crabs. My cousin Patrick McNamara lives only a few hours away in Massachusetts, and he is a diehard fisherman. The man compresses a five-day work week into four twelve-hour shifts in order to have three solid days to fish. He’s been known to sit on a beach in freezing rain for days on end to catch a run of striped bass. If anyone could help me break my losing streak on carp, it was Patrick.
From Connecticut I drove to Wilmington, Massachusetts, with one quick stop at a tackle shop. Within minutes of my arrival, Patrick suggested we try to catch the evening bite in a trout stream a few minutes away. I don’t think I’d even dropped my backpack from my shoulder. I’d come to the right place.
We hit the trout stream and took home a few nice rainbows. I had just finished gutting them when he had me back in the car to go fish for eels and bullhead catfish on Silver Lake — in the dark. The next morning we drove to the Concord River to a spot Patrick promised was loaded with carp.
His friend Justin Torname came along. We brought our heavy surf rods in anticipation of heavy carp. I also brought one of Patrick’s much lighter spinning rods, in case there was anything else to fish for.
Patrick’s bait of choice was oatmeal. I didn’t see how it would stay on the hook, but it was a simple matter to roll the stuff into a little ball and slip it onto the hook. Even underwater, the ball held together for a long time.
Patrick had the first bite. He grabbed the rod from its holder in the riverbank and started muscling in the fish. The rod was bent over so far that I thought it would break. Within a few minutes, he’d fought the thirty-inch fish to shore. Justin scooped it up with my landing net.
Seeing a new species up close and personal is always amazing to me. This fish had a yellowish face and a downward-oriented mouth with a couple of short barbels (small protrusions on the lip). What we were looking at was a common carp, not a grass carp. Not the same species, but close enough to get excited. Common carp are native to central Europe and are just as invasive as their cousins are. I killed it quickly with a knife to the brain. (I consider this to be more humane than the standard decapitation, and it exposes less surface area on the interior to potential bacterial contamination.) It’s a testament to the size of these fish that it took me a good five minutes to extract the four-inch hunting knife from the carp’s head.
Justin soon had a smaller carp, then Patrick hauled in a mirror carp. At first glance, the mirror carp looks like a different species. It has very few scales, which are widely distributed over its body, as opposed to most other carp, which have plenty of scales close together. In fact, mirror carp are simply a kind of common carp that has been bred by humans for its lack of
scales.
Carp don’t chase down their food. They are mostly herbivorous, though all species will swallow invertebrates and even smaller fish if they have the opportunity. They’ll also take a worm on a hook now and then. Anyone fishing for them should cast the bait and then leave it alone for a while, so I put my ball of oatmeal on its hook and let it settle to the bottom of the river. I rested the rod on a forked stick to wait for a bite. With my hands free, I decided to see what I could catch with a rubber worm and the lighter rod I’d borrowed from Patrick.
This turned out to be a mistake. Hoping for a bass, I hooked what I can only presume was a good-size carp. The light rod strained at the heavy weight, bent almost double, then snapped off. The line broke with it. I stared in disbelief at the dark, blank water for a moment before reaching into my pocket for a twenty-dollar bill, which I handed to Patrick as compensation for his rod.
We took a few more common carp before stopping for the day. Back at Patrick’s house, we cleaned the fish. I froze enough to fill the cooler for the trip home to Virginia a few days later.
At home, I smoked some of the carp, and it went nicely on toast for breakfast. There was no foul taste, and for a fish so big, I didn’t find it to be at all bony. It tasted as good as any other common whitefish, though a bit blander than the game fish, such as crappie and sunfish, that American fishermen are accustomed to eating.
As for the carp in my parents’ pond, the battle continues. In addition to nets, standard tackle, snag hooks, and corn, I’ve chummed oatmeal balls and anything else that ought to work. The fish dive and disappear as soon as I show up.
Many American anglers think of carp as, well, carp, and fail to recognize the various species. Each has a story behind its introduction and may require a different approach to catching it. Common carp were brought to the United States much earlier than were grass carp. German immigrants were accustomed to eating and fishing for them back home and first released them into the wild in the 1830s. Later that century, there was a series of efforts by the federal government to introduce common carp to American rivers. They were touted as a miracle food that would feed a growing country. Carp do indeed grow very large very quickly and can provide a lot to eat with one catch. But carp never became as popular a food as the government had hoped.
The carp that most recently is loathsome to Americans is an invasive species called the silver carp. This Asian native is notorious for leaping high into the air at the sound of an approaching motorboat. Seeing one fish do this is remarkable. When a hundred are leaping at once, it’s downright surreal.
Silver carp were brought to this country, for aquaculture purposes, in the 1970s. At the time, the species was appealing because of its astounding efficiency at converting suspended phytoplankton in the water into fish flesh. It doesn’t need to deliberately feed; it’s equipped with a unique spongy pad on its gills that soaks up the finest of algal particles from the water as the water passes into the mouth and through the gills. This fish literally eats as it breathes.
Aquaculture researchers looked at this trait and the rapid growth of silver carp as being ideally suited to turn wastewater treatment facilities into centers of food production. The high phosphorus content of the sewage resulted in huge blooms of plankton, which a carp could transform directly and rapidly into protein, growing up to a foot in length in its first year of life.
From the aquaculture perspective, this plan worked extremely well. The fish thrived in the wastewater ponds. There were, however, two problems. First, the FDA didn’t even want to discuss the idea of allowing the carp to be sold as food. After all, let’s face it, these fish were swimming around in water contaminated with human feces. Who wants to eat the poop fish?
The second problem was that despite the research that private businesses and federal agencies had conducted in advance, the fish escaped into the wild, and did well there, too. Nobody had predicted or even thought this would happen, mostly because silver carp didn’t seem to spawn readily outside of their native range. Research had suggested that silver carp wouldn’t be a problem if they escaped. One of the funny things about silver carp, though, is that even when they’re hardly spawning at all, you still end up with a lot of fish. The fry grow so fast that they quickly reach a size that protects them from most predation. When they’re still small, they don’t need to stray far from protective cover in order to feed (especially if there’s a lot of phytoplankton around for them to take in as they breathe).
Eventually, it became clear that the silver carp in the wastewater treatment ponds were spawning and that the eggs were drifting many miles downstream. The mature fish became established in rivers all over the Midwest, and in some stretches of river, they now constitute up to ninety-five percent of the animal biomass.
The stories I had heard about invasive silver carp sounded too strange to be true, especially the one about their habit of leaping out of the water in response to the sound of a boat’s engine. Imagine: enormous silver fish hurtling through the air at speeds fast enough to kill somebody and sometimes jumping into a boat. A refreshing change from conventional fishing, that’s for sure.
After watching grainy YouTube videos of these leaping carp, I desperately wanted to see the phenomenon for myself. I also wanted to eat one. Carp in general have a reputation among American fishermen for being inedible, even though most of those fisherman have never actually tried it. I don’t dismiss anything that moves as a food source until I’ve eaten it myself.
Out of the blue, I received an invitation from Jim Low, whom I had met at an outdoor writers conference in Utah. Jim is president of the Outdoor Writers Association of America, and also happens to be the print news coordinator for the Missouri Department of Conservation. Would I like to come out to Missouri for a few days and see these silver carp in action? Would I like to cook up a mess with one of the agency’s biologists?
I told Jim I’d be hitting the road as soon as humanly possible.
I didn’t even have to pack. By that time, I’d been on the road hunting and fishing for alien species for the better part of a year. The crab traps, fishing rods, guns, camping gear, and spices lived in the car. My suitcase hadn’t been emptied in months.
I made the eight-hundred-eighty-eight-mile drive to Columbia, Missouri, in two days. There was a time when I would have tried to do it all in one, but during my adventures in the last year, I had come to enjoy a lot of small things about being on the road. Eating at run-down old barbecue joints and roadside fruit stands. Pulling off to check out a state park, curious after seeing a sign. Picking up a hitchhiker on those rare occasions when there was room for a passenger. You miss out on those things when you try to rack up almost nine hundred miles in a single day. Not to mention that driving as you’re falling asleep is a recipe for disaster.
Once I’d gotten out of the familiar mountains and coal country of Virginia and West Virginia, the landscape was new. I crossed a river and went through a big town full of smokestacks and soon found myself in the midst of low, steeply rolling hills covered with grass and dotted with stands of hardwoods. I thought of hills like these as foothills — a prelude to mountains a short distance away. But these hills continued on as far as I could see.
I was into real horse country now and closing in on Lexington, Kentucky. The road cut through blasted-away sedimentary rock with unfamiliar layers of geological stories; I wanted to pull over and climb onto those man-made cliffs and look at the rocks up close and touch them. On an interstate highway, though, that’s usually frowned on.
Eventually those low grassy hills gave way to more trees until, suddenly, I became aware of the absence of hills with that keen, eerie sensation that is understood by anyone who grew up surrounded by mountains. The landscape was flat and open to the wide sky above. I was into Indiana, then Illinois. Cornfields lined the road, most of them low and brown with drought. I stopped in a town called Burnt Prairie, looking for lunch and finding only a gas station.
Missouri is a stat
e I still can’t quite get a handle on. Sometimes it feels like the Great Plains and other times it seems like the South. Even the accents are all over the map.
I met Jim in the parking lot of a Department of Conservation field station in Columbia. We were quickly joined by biologist Vince Travnichek, who manages the field station. One of Vince’s employees, Kevin, drove a pickup truck into the lot with a surprisingly large flat-bottomed boat in tow. We loaded the boat and truck with gear and drove to a tributary of the Missouri River that Vince thought would yield some silver carp.
Vince is a slightly portly man of middle age who seemed quite cheerful for someone who had given up caffeine a few days before. Decades into a career in biology, he still had an obvious enthusiasm for his field, apparent whenever the subject of fish was raised.
We backed the boat down a ramp into the water and the men began setting up a pair of long steel booms off the bow. This was the electrofishing gear — dangling metal tubes like wind chimes that touched the water in order to conduct electricity into it. In fact, the whole boat was designed specifically for electrofishing. Now I was getting very excited; I’d long wanted to see this unusual fishing method in action.
Electrofishing is used by biologists to zap anything within range of the current. This causes the fish to rise to the surface, where they can be observed. Vince assured me that the fish (with one exception) are only stunned and more than ninety-nine percent of the fish he zapped while sampling would soon swim away and go about the rest of their lives with no trouble at all. The one exception is silver carp. For reasons not fully understood, they have a high mortality rate over the few days after being zapped. This was okay by me.
It turns out that electrofishing is not the silver bullet I had thought it was. The current doesn’t go very deep, and bottom dwellers usually aren’t affected by it. Catfish, in particular, are underrepresented in electrofishing surveys. But this thing was still incredibly cool. Once we were under way, Jim and Vince flipped on the current, and a steady stream of baby shad bubbled up behind the electrofishing booms. I stood with a long-handled net ready to scoop up anything interesting. I handled a longnose gar for the first time. I saw buffalo fish and freshwater drum for the first time.
Eating Aliens: One Man's Adventures Hunting Invasive Animal Species Page 9
