Sun, May 29, 2011 - Page 13 News List

DNA testing reveals fishy business practices

Studies conducted by researchers using new gene sequencing techniques show that 20 to 25 percent of the seafood products they check are fraudulently identified

By Elisabeth Rosenthal  /  NY Times News Service, NEW YORK

Grouper is weighed on a scale in the New Fulton Fish Market in the Bronx borough of New York.

Photo: Bloomberg

Scientists aiming their gene sequencers at commercial seafood are discovering rampant labeling fraud in supermarket coolers and restaurant tables: Cheap fish is often substituted for expensive fillets, and overfished species are passed off as fish whose numbers are plentiful.

Yellowtail stands in for mahi-mahi. Nile perch is labeled as shark, and tilapia may be the Meryl Streep of seafood, capable of playing almost

any role.

Recent studies by researchers in North America and Europe harnessing the new techniques have consistently found that 20 percent to 25 percent of the seafood products they check are fraudulently identified, fish geneticists say.

Labeling regulation means little if the “grouper” is really catfish or if gulf shrimp were spawned on a farm in Thailand.

Environmentalists, scientists and foodies are complaining that regulators are lax in policing seafood and have been slow to adopt the latest scientific tools even though they are now readily available and easy to use.

“Customers buying fish have a right to know what the heck it is and where it’s from, but agencies like the FDA are not taking this as seriously as they should,” said Michael Hirshfield, chief scientist of the nonprofit group Oceana, referring to the US Food and Drug Administration.

On Wednesday, Oceana released a report titled Bait and Switch: How Seafood Fraud Hurts Our Oceans, Our Wallets and Our Health. With rates of fraud in some species found to run as high as 70 percent, the report concluded, the US needs to “increase the frequency and scope” of its inspections.

DNA bar coding, as it is called, looks at gene sequences in the fish’s flesh.

“The genetics have been revolutionary,” said Stefano Mariani, a marine researcher at University College Dublin, who has published research on the topic. “The DNA bar coding technique is now routine, like processing blood or urine. And we should be doing frequent, random spot checks on seafood like we do on athletes.”

Policing the seafood industry has historically been challenging because even the most experienced fishmongers are hard pressed to distinguish certain steaks or fillets without the benefit of scales or fins. And many arrive in supermarkets frozen and topped with an obscuring sauce.

Older laboratory techniques to identify fish meat looked at the mix of proteins in flesh samples but were unreliable, expensive and cumbersome. Investigators often relied instead on laborious legwork, tracking inconsistent fish names on paperwork as seafood moved across international borders. Eighty-four percent of seafood consumed in the US is now imported, often passing through a multistep global supply chain.

With the new genetic techniques, the gene sequence found in a fish sample is compared with an electronic reference library like that maintained by the International Barcode of Life Project, which now covers 8,000 varieties of fish compiled by biologists over the past five years. The testing is now relatively cheap: Commercial labs charge about US$2,000 for analyzing 100 fish samples, for an average of US$20 apiece, but the cost is under US$1 per sample for labs that own the equipment.

Douglas Karas, a spokesman for the FDA, said in an e-mail that the agency had been working with scientists to “validate” DNA testing for several years. It recently purchased gene sequencing equipment for five FDA field laboratories and hoped to use it “on a routine basis” by the end of this year.

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