Western Australian authorities vow to track down 10ft shark that killed US diver and may have taken 64-year-old swimmer A great white shark killed an American diver in the second fatal shark attack off Western Australia in 12 days. A witness on a dive boat saw “a large amount of bubbles” before the 32-year-old man surfaced with obviously fatal injuries, Western Australia police sergeant Gerry Cassidy said. People on the boat described the shark as a 10ft great white. It struck off the resort of Rottnest Island, 11 miles from a Perth mainland beach where a 64-year-old swimmer is believed to have been taken by a great white on 10 October. The diver who died was staying in Perth on a working visa. Police would not release his identity. It is unclear whether he was killed by the shark that is believed to have taken Bryn Martin as he made his regular morning swim from Perth’s Cottesloe Beach towards a buoy about 400 yards offshore. But an analysis of Martin’s torn swimming trunks recovered from the seabed near the buoy pointed to a great white shark being the culprit. No other trace of Martin has been found. “It’s a cloudy old day today, which is the same as we had the other day with Cottesloe, and they are the conditions that sharks love,” Cassidy said yesterday. It is the third fatal shark attack off Western Australia in less than two months and the fourth in 14 months. Fatal shark attacks average fewer than two a year nationwide. Colin Barnett, the leader of Western Australia state government, said the shark would be killed if possible. Great whites can grow to more than 20ft in length and 5,000lb in weight. They are protected in Australia, a primary location for the species. Associated Press Australia Oceans guardian.co.uk