In the late 1960s, the U.S. government dumped 15,000 barrels of nuclear waste into those depths. "If animals are subjected to nuclear waste, this could cause genetic mutations and abnormal growth. The big females had returned to an area once famous for monster sharks until overfishing wiped them out. "In the past, this is the place you came to catch monster sharks," O'Connell said. But all the evidence we are seeing is telling me that all these big sharks might be back.