Shark attacks man off northern Sydney

A Sydney father attacked by a shark on the northern beaches has spoken about the ordeal that not only endangered his life but that of his son.
Paul Welsh was surfing with his 10-year-old son, close to shore, when the shark attacked.
"I was pushing my son on to waves and it just belted me from behind," Mr Welsh told The Manly Daily minutes after the attack.
"I grabbed on to the pinnacle of a rock and held on as it tried to drag me out ... and I won."
Police said the 46-year-old man was bitten on the left leg by a 130cm shark off Mona Vale about 8am (AEDT) on Thursday.
A spokeswoman from NSW Health told AAP the man was recovering well and would be out of Mona Vale Hospital "by the end of the day".
Police said they were still waiting to speak to the man.
Surfwatch Australia director Michael Brown, who witnessed the attack, told AAP the shark hit the man "like a freight train".
"This shark had come in round the coast, drawn in by all the baitfish," he said.
"It's come up underneath him and it's just shot straight up into him.
"Luckily he had the chance to grab on to a rock. He's hanging on to the rock for grim death. He's got the shark hanging on the back of him, thrashing around in the water."
Mr Brown said his knowledge of the conditions stopped him going out in deep water with his son.
"Because I do the shark patrols, I knew there were a lot of baitfish out there," he said.
He said the information he was privy to should be made public.
"The only reason my son and I weren't in the line of fire was because of what I know," he said.
"I had an opportunity to keep my son safe because I knew there were baitfish off the beach.
"There needs to be a system in place where we can report which beaches have high concentrations of baitfish so that anyone who wants to go to the beach can go to a website and make an informed decision."
Eyewitnesses speculated the shark may have been a white pointer, but Taronga Zoo marine expert John West said it was more likely to have been a bull shark.
"What normally occurs in those sort of areas, particularly estuaries, is whalers, particularly bull sharks," he told AAP.
"Bull sharks are notorious for moving around those areas and have bitten quite a number of people over the years.
"This is the period of time that they're here. As the water cools, they head back north."
Mr West said further investigation would lead to the type of shark being identified.
"They may have found a tooth in the wound that they were treating," he said.
"If that's the case, we'll be able to identify the shark specifically."
NSW Primary Industries Minister Steve Whan said the type of shark had not been determined after failed attempts by scientists to locate it.
"There has been some aerial work on that beach to see if they can spot that shark," he told reporters on Thursday.
"They still have to confirm firstly whether a shark was involved and then what type of shark."
Mr Whan said the aerial surveillance program recently implemented across NSW beaches has not affected the number of reported shark attacks, even though the number of attacks in the past year is down.
"We have trialled aerial surveillance but it has to be said on the initial evidence there wasn't much of an impact," he said.
He said swimmers could avoid coming into contact with sharks by not swimming at dawn or dusk.
In February last year, navy clearance diver Paul de Gelder lost a hand and a leg and was lucky to survive after being mauled by a 2.7-metre bull shark in Sydney Harbour.
Just a day later, 33-year-old surfer Glenn Orgias was attacked at Bondi Beach by a 2.5-metre great white that shook him and nearly severed his left hand.