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.

• Click here to continue reading this story