GOLDEN POND, Ky. (AP) — Like a slow-motion, underwater cattle drive, wildlife officials in a half-dozen aluminum boats used pulses of electricity and sound on a recent gray morning to herd schools of Asian carp toward 1,000-foot-long nets.
The ongoing roundup on wind-rippled Kentucky Lake opens a new front in a 15-year battle to halt the advance of the invasive carp, which threaten to upend aquatic ecosystems, starve out native fish and wipe out endangered mussel and snail populations along the Mississippi River and dozens of tributaries.
State and federal agencies together have spent roughly $607 million to stop them since 2004, according to data compiled by The Associated Press. Projects in the works are expected to push the price tag to about $1.5 billion over the next decade.
That's more than five times the amount predicted in 2007 when a national carp management plan was crafted, and no end is in sight. Programs aim to reduce established populations and prevent further spreading, but wildlife officials concede they may never be able to eradicate the prolific fish.
Much of the focus has been on limiting their northerly migration and keeping them out of the Great Lakes, where experts say they could devastate a $7 billion fishing industry. That effort features an underwater electric barrier near Chicago, water sampling for carp DNA, subsidies for commercial fishers and experiments with a mass roundup-type harvest.
It has been largely successful, although the lakes remain vulnerable and grass carp — one of the Asian varieties — have been spotted in Lakes Erie, Ontario and Michigan.
Less money and attention have been paid to the carp's virtually unchecked spread east and west into the Missouri and Ohio rivers, among others.
Asian carp were imported to the U.S. in the 1960s and 1970s as an eco-friendly alternative to poisons for ridding southern fish farms and sewage lagoons of algae, weeds and parasites. They escaped through flooding, deliberate stocking and other means.
"It was a dumb idea," said Joel Brammeier, president of the advocacy group Alliance for the Great Lakes. "Even back then, biologists understood the risks of bringing live, non-native animals into the country. It should never have happened."
Greg Conover, a U.S. Fish and Wildlife Service biologist who oversaw development of the national Asian carp strategy, realized how abundant they were becoming in the Mississippi River as he studied native paddlefish in the 1990s.
"At first there were no carp, then we were catching a few carp here and there, then eventually we were filling the nets with carp and no paddlefish," he said.
The catchall term "Asian carp" refers to four different invasive species — bighead, black, grass and silver carp.
Sport anglers are feeling their impacts. Scientists reported that carp in the upper Mississippi are out-competing prized native fish such as yellow perch and bluegill. And silver carp hurtle from the water like missiles when startled by boat motors. Collisions have broken noses, jaws and ribs.
"That has hurt the tourism industry," said Ron Brooks, Kentucky's aquatic nuisance species program director.
There are no precise estimates of Asian carp populations in U.S. waters, but there are believed to be millions. At times, they've totaled up to 90% of all fish populations on some backwaters of the Mississippi River. On two large reservoirs in Kentucky last year, commercial fishermen brought in 6 million pounds of Asian carp.
