LUNA PIER, MI -- Whenever Dave DeLong brings in one of his Maumee Bay seine nets, there's almost always one or two distinctive bright orange fish swimming around the writhing mass of bullhead, catfish and carp.

DeLong, a Lake Erie commercial fisherman, makes a living hauling live fish to the Luna Pier Harbor Club, where his catch is weighed and sold. He's been fishing for 45 years on Lake Erie and goldfish have been part of that catch every year.

"We used to throw them away," he said.

Not anymore.

Goldfish -- larger versions of the species found in household aquariums -- have been a part of the Great Lakes ecosystem for a long, long time. While that's really no secret, most would be surprised to learn just how many actually inhabit the bi-national waters.

In 2015, Michigan and Ohio commercial fishermen netted 113,800 pounds of goldfish in western Lake Erie, the only Great Lake that yields enough to market. Michigan waters produced about 78 percent of that catch, or 88,791 pounds.

In Ohio, fisherman out of the Port Clinton area netted about 22 percent of the Lake Erie catch, or about 25,100 pounds. While goldfish are found in Pennsylvania, New York and Ontario waters, the fish is not commercially sought.

The 88,791 pounds caught in Michigan brought in $68,369 at the dock.

"It's a mainstay as part of the commercial fishery down there," said Tom Goniea, fisheries biologist with the Michigan Department of Natural Resources.

"Goldfish flirts with breaking into the top 5 most lucrative species in Lake Erie every year, from a Michigan standpoint."

Goldfish, or "gold carp" as they're also called, are by no means the first non-native species to become lucrative in the Great Lakes. Atlantic and Pacific salmon, brown trout and rainbow trout are all native to elsewhere but are currently sought by anglers and stocked in one or more of the lakes.

Some researchers believe goldfish were the first foreign fish species introduced to North America; possibly as early as the late 1600s, although most sources peg the introduction date closer to the mid-1800s. The small, orange fish swimming around fishbowls is a domesticated version of a less colorful carp originally bred for ornamental ponds more than 1,000 years ago in China.

According to the U.S. Geological Survey, the U.S. Fish Commission (precursor to the U.S. Fish & Wildlife Service), raised and distributed goldfish in the late 1800s to meet demand for aquarium and ornamental lake fish.

Wild fish can grow to several pounds and most are thought to be Prussian carp. However, there's confusion among biologists over the years as to the exact taxonomy of wild goldfish, which may be a hybridized version of different carp species. Regardless, they are found throughout much of North America, but most heavily in western Lake Erie. They are sometimes found in Lake Huron and tributaries, notably by commercial netters in Saginaw Bay.

In Michigan, goldfish are not a pest species, but the state has prohibited their use as bait. Ohio does not have a similar ban. However, because goldfish are not native species and can reproduce easily in lakes, most states advise people not to flush their pet fish down toilet bowl or release them into local waterways.

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"I think most purists and biologists would prefer not to have them as part of the wild environment, but I'm not sure they meet the classification of harmful," said Goniea. For that reason, they aren't, per se, "invasive."

Of the goldfish caught in Lake Erie, most are actually not very colorful. Many appear gray or olive drab, said Ohio DNR fisheries biologist Travis Hartman.

The fish inhabit shallow waters and are usually plentiful in the spring or fall.

"Normally, they are more of a bycatch," Hartman said.

Harvested goldfish are shipped to wholesale markets in New York or Los Angeles. Dale Trent, a fish processor in Sandusky, said 90 percent of the Ohio catch is sold at the New Fulton Fish Market at Hunts Point in the Bronx.

Trent sells gold carp for about $1 per pound and said the small market for the fish seems to be increasing. Asians buy them, he said. Some processors turn gold carp into kropek, a kind of cracker. (No, not that cracker).

Mike Shafer of Shafer Fisheries, an Illinois wholesaler, said the demand for gold carp outstrips the supply and he'd like to see them farm-raised.

"There's nothing negative about eating carp," he said. "Other than the bones."

In Michigan, DeLong said goldfish only developed commercial value in the past 20 years. The state's catch has risen from about 8,000 pounds in 2001 to a peak of 90,700 pounds in 2009, with fluctuations year to year.

He's glad some people like them. He tried to cook a goldfish once. Once.

"We've been catching 'em forever," DeLong said. "Now, we're selling 'em. It's just another species we can make a few dollars off."

Garret Ellison covers government, environment & the Great Lakes for MLive Media Group. Email him at gellison@mlive.com or follow on Twitter & Instagram