Let us review the litany so far: It is big, growing to the size of a golf bag; it is mean, with razor-sharp teeth and powerful jaws that can bite other fish in half; it is bizarre, able to crawl on its belly like a snake; it is resourceful, able to survive out of water for days; and, of course, it is dangerous, because it attacks people.
The subject of all this carnival barker hysteria is Channa argus, the northern snakehead, a fish native to Southeast Asia. A pair of the snakeheads entered the wild in the United States about two years ago when they were released into a pond in Anne Arundel County, Md. There, they apparently have become quite comfortable, because they and their descendants have been terrorizing local fauna and human residents alike ever since.
Maryland Department of Natural Resources spokesman John Surrick told United Press International the unidentified individual who dumped the snakeheads in the pond probably had purchased the fish to eat -- snakehead is a delicacy in its native lands -- but set them free instead.
Surrick said, "We have identified young of the year and have caught about 100 of them. There appears to be at least one adult and an unknown number of juveniles ... We have no evidence that they are anywhere other than the pond. We've done some sampling in the Little Patuxent River, which is nearby, but we didn't find any snakeheads there."
The state has assembled a scientific advisory panel to decide how to deal with the invaders. At their first meeting last week, it was suggested the pond be poisoned with the chemical Rotenone.
Difficult though it may be to defend the creature becoming known as the Godzilla of the piscine world, the snakehead did not ask to be dumped in a Maryland pond half a world away from its accustomed home. Once freed, however, it has been doing what all creatures do -- attempting to survive.
As far as can be ascertained, there are no references to snakeheads in the works of William Shakespeare. If there were, America might have become acquainted with them much sooner. One hundred starlings were released in Central Park in 1890 by a group of Anglophiles whose intention was to introduce to North America all species mentioned by Shakespeare.
The motivation for this idea has been lost in the mists of history, but the results are evident. The "Audubon Field Guide to North American Birds" notes of the starling, "Conditioned by centuries of living in settled areas in Europe, it easily adapted to American cities ... it has spread over most of the continent. Its large roosts are often located on buildings and may contain tens of thousands of birds. These congregations create much noise, foul the area, and have proved difficult to drive away. Starlings are aggressive birds and compete with native species for nest cavities and food. There has been much debate regarding their economic value, but their consumption of insects seems to tip the balance in their favor."
Perhaps the snakehead should be viewed from a different perspective: America is a nation of immigrants and each new wave has brought with it disruptions of many kinds, beginning with smallpox, measles and other devastating diseases unleashed on natives by the first arriving Europeans. C. argus merely represents the latest character in a long drama.
According to a recent paper by Cornell biologist David Pimentel and three other authors, "Invading non-indigenous species in the United States cause major environmental damages and losses adding up to more than $138 billion per year. There are approximately 50,000 foreign species and the number is increasing. About 42 percent of the species on the threatened or endangered species list are at risk primarily because of non-indigenous species."
Most of these invaders -- about 25,000 -- are plants and about 20,000 are microbes. But they also include birds, such as the aforementioned starling, as well as arthropods, mollusks and mammals. Domestic cats fall into this category. Even though they kill an estimated 250 million birds a year, there is no groundswell to eradicate Felix domesticus from our shores.
Cats are here to stay because they are lovable and cute, while the unfortunate, ugly snakehead has become the poster child of invasive species. There are lots of nasty organisms out there making meals of our naive local flora and fauna: Dutch elm disease, yellow thistle, mongoose, green crabs, gypsy moths and those blasted starlings.
Barry Myers Rice, an associate scientist for The Nature Conservancy's wildlands invasive species team, told UPI, "The problem is when these organisms go to where they are not a native ... the native organisms do not know how to deal with the intruder."
Rice said snakeheads look like the bad boy on the block because in their new habitat in Maryland, there are no predators or pathogens that control them. However, "Where these fish come from in Asia, they're not monsters. Life happens in their native areas."
In fact, it can be quite difficult for a new species to become established in an unfamiliar habitat, Rice noted. When scientists try to introduce biological organisms to control undesirable plants, for instance, only about one-third of them are able to establish themselves. If an invasive species can acquire a toehold, however, it can be extremely difficult to eradicate it, and that toehold does not have to be very extensive.
"Once the population of invaders gets to a surprisingly low threshold ... you will not be able to stop the invasion," Rice said. "With plants, for example, if it thrives in as little as two square miles of scattered area, it is probably already unstoppable. The best way to deal with invasives is prevention."
Rice retains a surprising admiration for the creatures. "One thing to remember about these snakeheads and any invasive species is that the organisms are not bad things," he said. "They are very cool things. I would love to be snorkeling in Asia and see a snakehead".
Although there is some threat of extinction of native organisms by invaders, so far this has been a phenomenon on islands, not in large areas like continents and oceans.
Rice, a "Star Trek" fan, mused it would be nice if we could establish an experiment with the snakehead in a parallel universe to see what would happen in 15 years. "There is a reasonably good chance that these things are not going to survive," he said. "But there is also a good chance that they will not die out in five years. Then we will start losing biodiversity. In 15 years, the populations may equilibrate. Or maybe you'll have a pond with nothing but snakeheads and carp."
The problem, he said, is we cannot set up a parallel universe, so the snakehead experiment is unfolding in our midst. "These fish fit the criteria of a bad invader. We would not voluntarily introduce snakeheads ... We have seen non-native species drive native species to extinction enough times to say, 'Let's stick with the precautionary principle.'"
