Local residents Ray Drummond, Peter Frick and Peter Huxtable saw the 4m long shark while crabbing in the gulf.

While standing at the rear of the craft, Mr Huxtable noticed it approaching, moving very slowly past.

The shark circled the boat about five times before disappearing, Mr Drummond said.

The shark struck the boat from underneath, lifting the craft two feet high, damaged a crab net and was not seen again.

Mr Huxtable said the attack should prove as a warning for locals to keep a watch out in the coming summer months.

“Shark attacks are a real issue confronting locals,” he said.

“Remember, we are using their waters for recreation … so be cautious.”

Top O’ The Gulf Marine owner Robin Sharpe said sharks come to the area for a reason.

“Whether they were looking for snapper, I don’t know but it’s a warning to the community that you need to be careful.”

Mr Sharpe said sharks were more common around the winter months.

There had been no sighting around the foreshore area but people still needed to remember the sea is their habitat as well, he said.

Mr Huxtable said the sighting was a freak experience.

“We need to respect their space but not be afraid to go in the water.”

Port Augusta coastguard Janet McDonald added that sharks were not spotted often in the area.

“I think it’s a one off sighting, you shouldn’t be scared of the water but you should always be careful,” she said.

Should any more sightings take place, contact the coastguard on 0458 574 115.