Remember that red snapper you picked up for dinner last week? It was probably a red herring.
A provocative new genetic study by scientists at the University of North Carolina has found that most supermarket fillets sold as red snapper - one of America's priciest and most popular fish - are actually some other species.
The findings, published today in the journal Nature, might come as a shock to fish lovers. But not to government officials and industry veterans, who say that confusing names and "species substitution" - illegally passing off a cheap fish as a more expensive one - are as old as the industry itself.
"A consumer might be good at knowing that a piece of lamb is not a steak," says Philip Spiller, director of the Food and Drug Administration's Office of Seafood. "Very few people are very good at determining one fish species from another."
And mislabeling can throw off the important fish counts that government agencies use to help manage overfished species - including red snapper.
Peter Marko, the University of North Carolina biologist who directed the snapper study, said it began as a project in one of his graduate genetics classes. Marko had heard numerous tales about mislabeled seafood, including some about red snapper.
The fish, Lutjanus campechanus, swims among the coral reefs and rocky outcroppings of the Gulf of Mexico and Atlantic coast. Its tender white flesh typically commands a high price, a situation that Marko reasoned might boost the incentive for sellers to pass off an inferior fish as red snapper.
To find out, Marko and his students collected 22 fillets from nine supermarkets in Delaware, Florida, Illinois, Massachusetts, New York, North Carolina, South Carolina and Wisconsin.
The researchers extracted DNA from each sample and compared it to samples from GenBank, a database containing genetic sequences from all snapper monitored by the U.S. government.
To their surprise, the scientists found that 77 percent of the samples tested in the study were actually some other fish. Because the analysis has a statistical margin of error of 17 percent, the researchers concluded that "between 60 and 94 percent of fish sold as red snapper in the United States are mislabeled."
So what were those mystery fish? Again drawing on GenBank, the scientists found that most were other species of snapper, including the vermilion snapper, crimson snapper and lane snapper.
Some of these charlatans ply the same waters as the red snapper; others come from as far away as the western Pacific.
In a few cases, scientists couldn't determine what fish supermarkets were selling in place of red snapper.
Marko said he can't be sure whether the falsely labeled fish arrived at the supermarkets as a result of mistaken identity or deliberate deception. As a result, he said, the study "almost raises more questions than it answers."
Rick Sciulla, a 35-year veteran of the business who now oversees fish procurement for all of Maryland's Giant supermarkets, acknowledges that species substitution and other deceptions do occur, especially with a potential money-maker such as red snapper.
"You don't hear of it today like years ago," he says. "I would like to think that the industry is sophisticated enough now not to do that."
A few veteran fishmongers, including 71-year-old Bill Devine of Faidley's Seafood in the Lexington Market, say there will always be cheaters in the business. "They are like Ali Baba and the 40 Thieves," Devine says. "If someone can pass something off for a buck less, they'll do it."
Marko concedes his findings are suspicious. None of the snapper species he found masquerading as red snapper is a dead ringer for the more expensive fish. "Any trained eye should be able to easily discriminate those species," he says.
But Sciulla, the Giant buyer, says it's not always that easy, especially for grocery story employees and others who see the fish after it's filleted.
"I can take you to the fish case and cut five fishes," he says. "You'd never be able to match the carcass to the fillet."
The FDA, which oversees the seafood industry, says it keeps no statistics on fish fraud. "Quite frankly we are not actively aggressively looking for it," said Spiller, the Office of Seafood director. The FDA, says Spiller, requires the industry to label a fish with its common name and publishes a guide known as the Seafood List to help merchants.
But fish nomenclature remains a murky realm, says biologist Joseph Nelson of the University of Alberta, who chairs a scientific standards body known as the Committee on Names of Fishes.
Nelson says that the name of a fish can vary widely from region to region - depending on local custom. And the industry, always eager to sell more seafood, hasn't always helped clear up the confusion, he says.