"Forget the recession — the biggest threat to the American economy could be an attack of giant Asian carp.
Ugly, pushy and always hungry, these 100lb (45kg) beasts are evading the high-tech electrical defences that are supposed to stop them from swimming from the Mississippi River into the Great Lakes on the US border with Canada.
The result could be an underwater bloodbath, as the carp munch their way through entire species of rival fish and devour 40 per cent of their body weight in plankton every day.
Officials in the state of Illinois, who have taken to dumping poison in commercial waterways as a last resort, fear that the attack could lead not only to an ecological disaster but also to the collapse of the lakes’ $7 billion-a-year (£4.2 billion) fishing industry.
It gets worse: the only way to stop the killer carp, say environmentalists, is to close down the locks that connect the Mississippi to the Great Lakes — a move that could devastate the shipping industry and push up prices of iron ore, coal, grain and other goods.
“The impact is going to be large,” said Lynn Munch, a senior vice- president of the American Waterways Operators, which represents the US tug and barge industry. “It could definitely impact day-to-day living.”