9.16.2005

Aliens Invade

Last month, five illegal aliens were caught in Queens, skulking in the brackish water of Meadow Lake. After positive identification, New York State authorities cut them with knives until they bled to death. But the government had no other choice. For unlike the illegal immigrants found working the fields of central California, these were alien fish, whose continued survival could lead to dire economic and ecological consequences.

The exterminated individuals were Northern snakehead fish (Channa argus argus), native to Asia. Also known as “Frankenfish,” the MO of these monsters comes straight from the annals of science fiction. Their heads, covered in snake-like scales that give them their name, also hold a mouth full of sharp fangs. Their torpedo-shaped bodies grow as long as 40 inches, as heavy as 15 pounds. They can breathe air, and “walk” on land using their pectoral fins. They’ll survive for several months under iced-over waters or even buried in mud banks. Scarier still is an insatiable and indiscriminate appetite—they’ll feast on anything on land or sea, from fish and frogs, to ducks, and even small mammals. Secretary of the Interior Gale A. Norton was apt to call them, “something from a bad horror movie.”

Yet the public has taken little note of the Queens incident, and the media has described it with tongue-in-cheek. In an August 9th  New York Times article, for instance, Anthony DePalma makes light of the problem, writing “Lady Liberty…might have a hard time getting at all gushy about some of the most recent immigrants to the city.”

This mockery of the snakeheads is unfortunate, and surprising, because this isn’t the first time the fish have reared their ugly heads. Just three years ago, a tourist bought a snakehead at a fish market in Manhattan’s Chinatown. (Sold for about $9 a pound, steamed strips of fish are often combined with ginger and scallions in sweet soup recipes. Cooks like them for their freshness, since they can survive up to four days out of water.) The man took his new pet back to Crofton, Maryland to raise it. But there was a problem: No matter how much it ate—up to 12 goldfish per day—it wouldn’t stop growing. When he finally dumped the beast into a small pond behind a local shopping center, he had no idea he was breaking a state law, or that his act could lead to an ecological disaster for the entire Chesapeake Bay.

Sadly, most Americans are not now and have never been aware of the dangers caused by the introduction of invasive alien species. For hundreds of years, Europeans and Americans who ventured abroad have shipped slaves, gold and, yes, biological booty back and forth from their native lands. Take one romantic, if not odd, Eugene Schieffelin. In the late 19th century, this wealthy contributor to New York theatre was determined to give the New World all of the birds ever mentioned in the works of Shakespeare. Most couldn’t survive the American habitat. But he released 60 pairs of starlings (mentioned by Shakespeare just once, in Henry IV: “I'll have a starling shall be taught to speak…”) that would propagate to become our most abundant and annoying bird species, pushing out natives like bluebirds and martins.

Granted, creatures from afar are often romantic, novel, exotic—it’s why everybody loves the zoo. So an earnest public might ask, why not bring them here? What’s the big deal?

According to an extensive 1993 report by the Office of Tribal Affairs (OTA), over 900 exotic, free-ranging species have caused ecological or economic harm in the United States. To understand why, consult evolutionary theory. Alien species, by definition, did not evolve in or for our specific ecosystem. Thus, when thrown into a new environment—with a new climate, new food sources, new competition, new prey—their behaviors are unpredictable. Unsurprisingly, many cannot survive at all. But others are superbly equipped to travel, thrive and even dominate their new surroundings.

Take that wretched Northern snakehead, for example. In its native Southeast Asia, it lives in irrigation ditches and rice paddies. After the rainy season, these trenches dry out and the fish must migrate to a wetter place. Hence, for thousands of years, the creatures with fins that allowed them to flop around on land are the ones that survived. Similarly adaptive systems evolved in the snakehead’s digestive system, where it has an air sac that allows it to absorb oxygen when it’s out of water. The snakeheads, thus falling into the category of invasive foreign species, are a North American ecosystem’s worst nightmare.  

The biggest ecological problem with invasive species is the loss of biodiversity. In the 1960s, a “walking” catfish from Sri Lanka was exported to a Florida fish farm. Within 10 years, the catfish had spread to 20 Floridan counties. In the decades since, up to 90%--that’s 4,000 pounds per acre—of the area’s fish kill has consisted of the catfish. In Australia, a similar invasion has caused the rapid decline of native frog populations. There, a deadly virus was introduced to Queensland and transmitted to frogs by an imported fish. The telling part: the fish was not sold for eating, but for ornament.  

Another negative effect of invasive species is the destruction of natural resources. The Siberian gypsy moth, an insect that strips the leaves from spruce, larch, and fir trees, and in large numbers thus poses a great threat to coniferous forests, is ranked in the top three of Russia’s biological pests. The OTA’s report divulged that thousands of raw logs imported to the United States from Siberia carried--guess what?—Siberian gypsy moths.  

And for those who scoff at the ecological consequences, perhaps they’ll sit up when they hear the situation affects their pocketbooks. Loss of biodiversity often translates into loss of money, and lots of it. The Australian Brown tree snake, accidentally introduced to Guam in the early 1950s, now thrives there with up to 13,000 snakes per square mile. The snakes, by crawling on power lines, have caused more than 1,200 power outages since 1978. Since its arrival in 1892, the Cotton boll weevil has cost the U.S. cotton industry $13 billion; Zebra mussels—introduced to the Great Lakes from Caspian Sea water dumped from a transatlantic ship—have clogged American pipes since at least 1988, demanding utility repairs to the tune of $3 billion.

So what ever happened to those snakefish dumped in the Maryland pond three years ago? Officials knew they had to be eradicated, for fear of their spread. Because they can “walk,” they could have left the pond, crawled a mere 75 feet to the Little Patuxent River, and from there invaded the Maryland river system and Chesapeake Bay. The pond could have been drained, except some of the fish would have inevitably buried themselves in the mud until they could make it to the Little Patuxent. Electroshock treatments didn’t work, due to dense vegetation in the pond. Traps were used with some success, but authorities still didn’t know for certain that all of the fish had been killed. A complete purge came finally when they poisoned the entire pond using a plant-derived toxin called Rotenone.

If not public awareness, the incident in Maryland at least spawned legislation. Within a few months, a federal law was passed banning the importation of snakeheads. But for many working on the problem, the ban didn’t go far enough. California is one of 13 states where it is illegal to import, transport, or even possess a snakehead. The state’s Fish and Game Commission has argued that the federal ban lacks teeth, as the high volumes of fish are imported together, and the snakeheads are small enough to hide behind larger ones. As Miles Young, a lieutenant in the California Department of Fish and Game, told the Sacramento Bee: “it’s been an enforcement problem.”

Back in Queens, now a full month since the finding of the five new snakeheads, the problem rages still. Undoubtedly, kin of the five exterminated fish are lurking underwater, devouring what’s left of the carp, white perch, and pumpkinseed fish native to Meadow Lake. Now closed for fishing, activity on the lake consists solely of local biologists setting traps for more snakeheads. But so far, they’ve had no luck.

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