Palumbi is a marine biologist at Stanford University and the director of the Hopkins Marine Station in Pacific Grove, Calif. He has tested the veracity of seafood labels at venues ranging from huge, upscale grocery stores to small fish markets. As a practitioner of what might be called molecular forensics, he uses DNA “to see whether the things we assume are true really are,” and it’s time, he says, for the scales to fall from our eyes.