The war on sharks has been waged with shock and awe at times. When a shark bit or killed a swimmer, people within the past century might take out hundreds of the marine predators to quell the panic, like executing everyone in a police lineup in order to ensure justice was dispensed on the guilty party.

Eric Clua, a professor of marine biology at the École Pratique des Hautes Études in Paris, said the rationale behind shark culls in the past was simple: fewer sharks, fewer attacks. That reasoning also drives methods such as shark nets and baited hooks, which are currently in use at a number of Australian and South African beaches that are frequently visited by sharks. Nature, he notes, pays too great a price.

"They are killing sharks that are guilty of nothing," said Dr. Clua, who studies the ocean predators up close in the South Pacific.

Dr. Clua said he has found a way to make precision strikes on sharks that have attacked people through a form of DNA profiling he calls "biteprinting." He believes it's usually just solo "problem sharks" that attack humans repeatedly, analogizing them to terrestrial predators that have been documented behaving the same way. Instead of culling every bear, tiger or lion when only one has serially attacked people, wildlife managers on land usually focus their ire on the culprit. Dr. Clua said that problem sharks could be dispatched the same way.

This summer, Dr. Clua and several colleagues published their latest paper on collecting DNA from the biteprints of large numbers of sharks. Once a database is built, DNA could be collected from the wounds of people who were bitten by sharks, and matched to a known shark. The offending fish would then need to be found and killed.