Well before dawn, Todd Loop takes his fishing tug onto Lake Erie in pursuit of yellow perch, walleye and other delicacies a livelihood that has sustained his family for three generations but faces a future as murky as the freshwater sea on a moonless night.
Already ravaged by exotic species such as the sea lamprey and quagga mussel, the Great Lakes soon may be invaded by Asian carp, greedy giants that suck plankton from the water with the brutal efficiency of vacuum cleaners. Scientists are unsure how much damage they would do, but a worst-case scenario has them unraveling the aquatic food web by crowding out competitors and decimating a fishing industry valued at more than $7 billion.
Nowhere is the danger greater than in Lake Erie. Although the shallowest of the five lakes, its fish populations are by far the most abundant. That's why commercial fishing, which has faded elsewhere in much the Great Lakes region, is still alive in Canadian port towns scattered along the lake's northern shoreline.
But fishermen such as Loop, 48, wonder how long their cherished way of life will continue.
"We're just trying to survive and make a decent living," said Loop. "It's bad enough already, but if those carp get in here . it could be absolute devastation."
Commercial fishermen are already squeezed by the bad economy and regulations limiting the size of their catch. The number of fishing boats and employees has declined by about two-thirds in recent decades, and many of those who remain say they're barely hanging on.
The industry's downfall would be a crippling blow for places like Wheatley, where commercial fishing is not just a pillar of the local economy, but a cultural icon.
"It's absolutely vital that the commercial fishing industry remains strong here," said Barry Broadbent, owner of the Car Barn diner in Wheatley, where local perch is a menu staple. "It puts money in everybody else's pockets."
Lake Erie has relatively mild temperatures and plentiful supply of plankton, the foundation of the food chain, making it ideal fish habitat. In addition to perch and walleye, which the Canadians call pickerel, the lake teems with varieties prized by commercial and sport fishers alike: bass, trout, salmon, whitefish, smelt and more.
On July 31, boosters placed signs at the edge of Wheatley proclaiming it "the world's largest fresh water commercial fishing port." Ontario's oldest and largest fish processor, Great Lakes Fish Corp., shut down a month later in the town of 1,800 after operating just short of a century, idling 130 workers.
The closure was depressing for the tradition-minded community in which the industry provides spinoff jobs such as repairing nets and maintaining boats. Crews shop at local stores and eat at local restaurants.
Settlers established the first commercial fisheries on Erie's north coast in the mid-19th century. By the early 1980s, about 130 vessels operated across the region, employing some 3,000 workers. But the industry has declined across the Great Lakes as improvements in technology and equipment led to overfishing, invasive species took their toll and big operators bought up smaller ones.
To the Canadian fishers, a big foe is the system that sets annual quotas on the amount of walleye and perch that can be taken from Lake Erie to prevent excessive harvests and give both commercial operators and sport anglers a fair share. The limits are set by a committee with representatives from the province of Ontario and the states adjacent to the lake: Michigan, Ohio, Pennsylvania and New York.
Walleye catch limits have fallen drastically in recent years just 2.2 million fish this year, down from 9.9 million in 2006. Perch levels have fluctuated during the same period, but the committee warns of declines to come.
Some commercial operators insist there's fish aplenty and that the quotas, rising costs and the poor economy have pushed many to the brink. Those like Don Loewen, 69, wonder whether the fishing industry can even stay alive long enough for the invaders to make a difference.
"We will probably die before the carp get here," he said.
Bighead and silver carp, both Asian species, have migrated up the Mississippi River and its tributaries for decades. They're now on the Great Lakes' doorstep, threatening to enter Lake Michigan through Chicago-area canals and rivers.
Authorities are trying to repel them with electric barriers, poisons and nets. Five states are suing in federal court to close navigational locks that provide openings to the lake, a move ferry and barge companies fiercely resist.
If a breeding population takes hold in Lake Michigan, biologists say, they could find their way around the tip of Michigan's Lower Peninsula to Lake Huron, then south to Lake Erie. How long the journey of more than 700 miles would take is anyone's guess.
"They'll make it eventually. They're good swimmers," said Jeff Reuter, director of Ohio State University's Stone Laboratory.
This summer, the danger suddenly looked a lot closer. Biologists discovered Asian carp had advanced farther north than previously thought on the Wabash River in Indiana, which has a tributary that seeps into wetlands near Fort Wayne. They say the carp could slip across the marshes during floods and reach the nearby Maumee River. From there, it's a straight shot to Lake Erie.
"Of all the Great Lakes, Lake Erie would be the most feasible place for them to become established," said Roger Knight, a biologist with the Ohio Department of Natural Resources. The characteristics that make the lake hospitable to perch and walleye would apply equally to the carp.
An Asian carp infestation wouldn't necessarily doom other species, said Duane Chapman, a U.S. Geological Survey biologist. Sport fishing is holding its own in some places where carp have gained a foothold particularly the Missouri River, where anglers are still snagging catfish.
But experts agree it's likely that at least some species would suffer.
In Port Stanley, another Lake Erie fishing village, Larry Jackson's response to the Asian carp threat was a fatalistic shrug. At 73, he's seen lots of ups and downs in a lifetime of fishing. He was co-owner of the Wheatley processing plant that recently went bankrupt. A big financial hit, but he still has his lakefront fish shop and two tugs.
If the carp invade, Jackson said, he'll respond the only way he knows how: by catching them. Their flesh could be turned into patties and sold in Asia, where it's already popular, he said.
"If I'm given lemons, I'll make lemonade," he said. "If I'm given Asian carp, I'll make fish sticks."
Explore further: Avoid 'crape murder' with limited pruning