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Environment

What To Do With Invasive Asian Carp: Electrocute, Poison, or Bow and Arrow?

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http://youtu.be/nc-e8EGkLMo At 50 pounds, the Asian carp can pack up a punch--especially if you get caught in a cloud of jumping fish. "The air is so thick with fish that some bash together mid-flight, showering everyone with a snot-like splatter," writes Ben Paynter in a Bloomberg Businessweek feature on the invasive Asian carp. Damaged boats and injured boaters---broken noses and concussions are among the alleged crimes of the Asian carp---aren't even the biggest problems with the fish. The bottom-dwellers eat voraciously, starving the native fish and quickly outgrowing any natural predators. They're now in 23 states, and fears are that they will soon invade the Great Lakes. Drastic policies to protect the Great Lakes, such as completely rerouting the trade through Chicago's waterways, have made it as far as the Supreme Court even though tracking the fish's actual location is rather imprecise. (The Supreme Court rejected the request.) eDNA---e for "environmental"---detects the presence of DNA from Asian carp but it can't tell the difference between 1 and 100 fish or even between a live fish or a few scales. Instead, writes Paynter, researchers have resorted to brute force methods for counting fish in a river: electrocution and poison.

[N]ear a railroad track lined with shanty houses, sit three electric barrier stations. These are like mega-electrofishing units, paralyzing fish across the width of a river. Anything shocked will simply float back downriver. The river here is also flanked by 13 miles of ultrafine chain-link fence, meant to keep fish from other rivers from dumping into the channel above the fail-safe during floods. When a barrier was taken down for service in December 2009, state and federal officials launched Operation Silverstream, a 450-person effort to poison six miles of river with Rotenone, an industrial fish toxin. The attack used boats and pumps on the shore to inject Rotenone into the water. Its spread was tracked with a dye, and caged fish acted like underwater canaries. A neutralizer was applied downstream. The effort killed thousands of fish but found only one bighead carp near the barrier. After numerous eDNA hits around the Little Calumet River just a few miles from Lake Michigan in May of the following year, officials mounted Operation Pelican, poisoning a three-mile stretch of river, again without finding any Asian carp. When a bighead carp was netted above the quarantine zone in Lake Calumet in June 2010, officials tried a less noxious tactic. A large-scale fishing expedition lasted for days, but their nets came up empty.

Efforts to contain the Asian carp population include incentives for catching more of them. "Aerial bow fishing" and a "carp rodeo" where participants catch jumping carp with nets have killed thousands. But what do with the catch? Despite attempts to rebrand the fish for the dinner table, it hasn't really caught on in America. Ironically, one of the biggest markets for carp may be where they originated:

In the homeland of carp, there are hardly any wild-caught specimens available; canal systems are too polluted to support the species. American processors can buy carp for 13¢ per pound on the docks and get up to 92¢ per pound from mainland importers. “In China, we tell everybody that this fish is so fresh and has so much energy that it dances on the water,” says Harano, the marketer at Big River Fish, which recently received a $2 million state grant to expand its packing plant to handle an annual 30-million-pound contract for Beijing. “We market it a lot like you might Angus beef.” Their logo is a bald eagle clutching a fish in its talons while flying over the Mississippi River.

For more delicious (or maybe not so delicious) details about our carp problem, head over to Bloomberg Businessweek.

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