CHICAGO — The Asian carp infesting the major rivers of America didn't sneak into the country in the ballast of ocean freighters, as so many invasive species have. They didn't slowly invade through freighter locks and into the Great Lakes, as the sea lamprey did.
Decades ago, federal and state officials purposefully imported carp, which they believed were "the wonder fish."
The carp were imported because officials were eager to find a safer way than chemicals to control weeds, algae, sewage and parasites. Grass carp eat as much as three times their body weight in weeds each day, replacing the toxic chemicals commonly used for weed control.
But during the past four decades, not only have the Asian carp escaped into the wild, they also have expanded their reign to rivers and lakes across America -- as state and federal officials have stood idly by.
The next decade is a crucial time in the battle against the Asian carp. There is ample evidence that the fish could devastate the Great Lakes, and they might eventually dominate all the major rivers and lakes of North America.
The question now is whether government agencies will act quickly to protect the Great Lakes, or fail to head off the carp again and allow history to repeat itself.
'Wonder fish' comes to America
The four species of Asian carp that are now the scourge of Middle America -- silver, bighead, grass and black carp -- were first brought to the United States in the 1960s.
It started with grass carp, a fish that gobbles vegetation and could clean up America's weed-choked ponds and lakes.
To federal officials, the most important carp were the silver and bighead. They feasted on algae and sewage and satisfied a movement in the 1970s to use a chemical-free method to battle pollution. Bighead and silver carp would consume polluted organic material.
To U.S. and state wildlife officials, the Asian carp experiment was worth the risk. The fish were so effective at their jobs that Arkansas raised and released 380,000 of them in public waters and private fish farms.