Fishing Lines: In Wayne's world, they still fight invaders with bows and arrows

Wayne from Maine wouldn't believe me. It was hard enough convincing him that people deliberately fished for carp in the UK. But he wasn't fooled when I told him that after catching a carp, British anglers unhooked the fish on a soft mat and gently put it back into the water.

"You must think us country-boy Merkans are really dumb! Bad nuff fishin' for them deliberately, but puttin' 'em back? Now I know you're pullin' my whanger, Keith!" And he wouldn't be swayed.

American fishers have a slightly more robust approach to carp. Yes, they fish for them - but with bow and arrow. Carp are considered "trash" fish; killing them is on the same scale as squishing a mosquito.

Seems outrageous to us. Here, carp are revered, and large specimens are given names like Mary, Arfur and Heather. (I didn't dare tell Wayne that.) It's a bit harder to mistreat a fish that has the same name as a close chum or an adored girlfriend. But it seems that the Americans may not be so callous after all. Carp are invading North America, and aquatically causing more damage than a shoal of Al-Qaeda terrorists.

It all started back in Henry's Pond, near Newburgh, New York, in 1831 when the owner, Captain Henry Robinson, imported about 80 carp from France. The fish were then introduced to the Hudson River. Forty years later, official shipments were brought from France by the US Fish Commission. These stockings did not work, but as we know all too well, Americans don't give up easily, even when they're doing something daft.

They continued stocking until 1896. By this time, the carp had found the long, hot summers and an abundance of natural food to their liking.

By the early 1900s, carp had spread throughout the Great Lakes system. The only regions where you won't find them are Alaska, the Yukon and Northwest Territories. Cane toads and sparrows, cats and carp: you would have thought man would have learnt the folly of introducing alien species. But no.

Fish farms in the US have been using Asian carp to eat snails, which carry parasites and can kill stocks of other fish. And guess what? These carp escaped from Arkansas fish farms during flooding in the 1990s. They are multiplying like a calculator, and there's no practical way to get rid of them.

Take a look online at the flying Asian carp show *. A fishery biologist, Eric Leis, says: "They get excited by the vibration of the motors and the waves that go across the water, and they just jump."

They look like black carp, which are mainly plant and plankton eaters. They can grow to 80lb, certainly enough to attract anglers though hard to catch on rod and line. However, they compete with native species such as bass, crappie and sunfish for plankton. Another fishery biologist, Heidi Keuler, says: "They disrupt the ecosystem. Basically, they eat all the food."

* 49abcnews.com/news/2007/jun/19/flying_fish_fun_watch_dangerous_ecosystem