Every year the fins of up to 73 million sharks, ranging from endangered species such as scalloped hammerhead sharks and broadfin sharks to more common species from sustainable fisheries, are traded and sold to make shark fin soup, a traditional Asian delicacy. A common perception is that much of the fin trade comes from sharks caught in distant international waters—where rules governing fishing are a little less clear and a lot harder to enforce, complicating conservation efforts.

But a new study, published today in the journal Biology Letters, upends that notion by concluding that many of the fins found in markets in Asia, North America, and South America come from sharks caught closer to shore—within the territorial waters