Windang's Steven Fogarty was the victim of a 2m dusky whaler shark that was most likely competing for access to a school of fish, a NSW Government expert has concluded.Dr Vic Peddemors, who heads the shark research section of the Department of Primary Industries (DPI), visited Mr Fogarty's seaside home yesterday to investigate the attack.Mr Fogarty, 24, was attacked while snorkelling under Windang Bridge on Monday morning, suffering 40 puncture wounds to his right calf and cuts to his fist from fighting off the predator."There's no doubt the attacker was a shark," Dr Peddemors said. "Its top jaw has had at least three goes at Steven's leg and left crescent shaped wounds."He said based on the size and shape of the tooth marks, a dusky whaler was the culprit. The distance between the teeth and the width of the jaw indicated it was 2m to 2.2m long."We know from our research at the DPI that dusky whalers do go into large estuaries and would be quite comfortable swimming around here," he said.Despite the findings, he said a dusky whaler usually wouldn't consider biting a human, especially one that was almost the same size as its prey, given Mr Fogarty stands 181cm tall."They're just not designed to bite humans and don't interact with them often enough to want to do it," he said.Dr Peddemors said it was more likely the shark believed it was competing with Mr Fogarty for a school of fish."Steven was lying on the bottom looking at a school of bream and blackfish."It's possible the shark has mouthed him as if to say, 'This is my school of fish, get out of my way'."There's no chunk of flesh missing, and yet there has been three strikes on his leg."Mr Fogarty said Dr Peddemors' belief the shark had not set out to eat him might help him.After five days, Mr Fogarty says he still has nightmares and wakes in cold sweats."But I've got a good group of friends who visit every day to keep me company and take my mind off things."