03/18/2010 05:12 am ET Updated May 25, 2011

DNA 'Barcodes' Reveal Phony Fish Served Up On Menus

Scaled, sliced and hand-rolled, the eight most marketable species in the tuna genus Thunnus are prime candidates for honest error -- or bait and switch. On a plate, these wild tuna are almost identical, but sushi lovers especially prize the three species of bluefin tuna, whose annual catch was sharply curtailed last month.

To identify the premium filets, the museum researchers singled out a short piece of genetic code naturally found in fish cells that, for the first time, can reliably label each of the eight species like a grocery store's inventory tag.

The researchers call it a DNA barcode.