Brisbane, Australia (CBS) -- Updating the shark attack on the Gold Coast, the experts say the surfer is lucky to be alive. It could have been so much worse for Billy O'Leary. It's predicted the shark that savaged his leg was more than two and half meters long and could have easily killed him. Despite that his friends say he is in remarkably good spirits.

Surfers were back in the water at Mermaid Beach this morning, unfazed by yesterdays terrifying attack. Twenty-four hours ago, an afternoon surf with mates took a dangerous turn for Billy O'Leary after a shark took a huge chunk out of his calf.

Today he underwent surgery. They were surfing at dusk in murky water teaming with Bait fish, when Billy wiped out in the middle of the school, and was mauled.

They were the perfect conditions for an attack, it's still not known what type of shark it was, but it was big. Trevor Long says, "It looks like quite a large shark, that's a reasonable sized bite. I think he's very, very lucky man, that he's been able to survive this."

Bait fish usually attract larger predators, and when people see them starting to school they should leave the water, especially surfers. Long says, "If they see something fleeing that's what creates interest, and if you see a surf board going along the wave that can create an interest."

Billy O'Leary has even managed to see the funny side. Despite the attack, the surfing mates all plan to get back in the water.

The water had cleared considerably today from the stormy and murky conditions Tuesday, and there were certainly no signs of any schools of bait fish.