Massachusetts officials are using hi-tech tags to track the movements of two great white sharks near Cape Cod - the first time the fearsome fish have ever been tagged in the Atlantic Ocean.
The electronic tag uses satellite technology to record the travels of the sharks, allowing scientists to better understand their migratory patterns.
The sharks were spotted at the weekend by scientists investigating sightings off Monomoy Island in Chatham. Officials say a harpooner tagged them with help from a state shark expert.
Overnight a number of Massachusetts beaches were closed after four great white sharks were spotted Saturday off the coast - including the two that were tagged. An expert said they were up to 3 metres.
Sharks are common in Cape waters during summer, though great white sharks are relatively rare around New England.