THE shark attack on a surfer off Port Stephens on Wednesday was just a taste of things to come, according to three long-term members of the Hunter's fishing community.

And an aviator who runs shark-watching tours predicted it was only a matter of time before there was a fatality off the 32-kilometre Stockton Beach.

All four said the inevitability of more humans being attacked was based on a major increase in the number of great white sharks off the regional coastline.

South Australian Ben Morcom suffered deep wounds to his buttocks on Tuesday while surfing a break known as The Boulders, inside Port Stephens and adjacent to Yacaaba headland.

The National Parks Association said Mr Morcom was the third person in NSW waters to have a "brush" with a shark in the past two months.

Association spokeswoman Valerie Taylor said increased shark activity at this time of year was normal and the attack on Morcom "probably involved an inquisitive bull shark".

Port Stephens fishing commentator John "Stinker" Clarke, businessman Graham Duffy and Raymond Terrace fisherman George Trinkler said more juvenile great white sharks had been attracted to the area, following increasing numbers of salmon swimming up the east coast.

The three said they had seen salmon and shark numbers growing steadily in the past six years, since the State Government banned professional fish netting north of Sydney and a South Coast cannery closed.

Mr Trinkler said he had recently seen 25 great whites over a five-kilometre stretch of Stockton Beach in three hours.

"You see them in shallow water, in fact, I've seen a shark chase a school of fish onto Stockton Beach and then roll back in," Mr Trinkler said.

Steve Bazic, whose company runs shark-watching tours over Stockton Beach, said he wanted people to be aware of the potential danger.

"I've flown this coastline since 1984 and shark numbers have certainly increased in that time."