The Asian carp in question is more accurately known as the Bighead carp; of the five known species of carp in this country, all of them came from Asia. This includes the common carp, which was brought over in the 1830s and is now considered to be a native species. The Bighead carp (along with the Silver carp) were deliberately imported from Eastern China in the 1960s and 70s by catfish farmers and wildlife experts to improve water quality and to control aquatic vegetation. The problem is, these huge fish (with voracious appetites) escaped their enclosures in the 1990s (likely after a flood), and entered a number of waterways in this country, namely the Mississippi River. They're bottom feeders that reproduce freely, and they eat such a ridiculous amount of plankton that it disrupts the entire food chain, established long ago by the many species native to these ecosystems. These carp can range anywhere from 50-100 pounds, and they have an especially disturbing habit of responding to boat traffic by leaping out of the water and slapping their huge, scaly bodies into boaters or fishermen or skiers; a number of people have been injured by these giant, flying fish!
This is just one of many failed attempts to control one biological nuisance by importing a species that is not native to the area, which in turn becomes an even bigger nuisance than the pests it was brought in to control! I'm not in favor of indiscriminate chemical controls, either (like those deployed last night), but I'm afraid I don't have a satisfactory solution to the problem at hand.
So what is rotenone, exactly? According to this article from Reuters, it is a "natural poison that prevents fish gills from absorbing oxygen." It goes on to say that it is "used as a broad-spectrum insecticide and pesticide, kills fish and freshwater snails but does not harm other animals. It dissipates within two days, though authorities plan to introduce a neutralizing agent to speed up the process." More specifically, it is a natural pesticide derived from the roots of tropical and subtropical plants and is used in organic gardening, on household plants, and as flea and tick control on pets. The fish and insects affected by this toxin die slowly, but stop eating almost immediately.
Other sources (which I can't verify, so I won't list here) suggest that it may contribute to mammary tumors and changes in blood composition in pets that accidentally inhale or ingest the stuff, and may possibly be linked to Parkinson's Disease in humans who have had chronic exposure. The sentence that bothered me the most in all of my readings was:
"There is considerable controversy over the use of rotenone to kill non-game fish in water body management areas. One study found that the practice has a substantially harmful effect on biodiversity, in which several populations of the native fish showed negligible signs of recovering stocks, while populations of all exotic species are up."
Invasive species are bad-- I get that-- but the killing of any living creature (an estimated 200,000 POUNDS of dead fish are expected to be recovered within the next couple of days!) on such an expansive scale just doesn't sit well with me, especially since early reports have turned up only one big, bad carp and scads of good, native fish. Surely there's a better way... right?