A letter to the South Coast Register in December last year alerted readers to the fact that the Shoalhaven River is not shark-free as many may have thought.

And his warning was confirmed this week by the NSW Fisheries Department and the MacDonald Aerial Patrol which is responsible for alerting swimmers to the danger of sharks along our coastline.

Claude Bird of North Nowra won't ever swim in the Shoalhaven River. He's seen far too many sharks since he started fishing here in 1946.

"It's true, I've seen quite a few sharks in the River. Particularly in the canal," he said.

"In fact I've caught some, one being a bronze whaler between five and six foot in length, while I was fishing for Jew fish.

"That was a long time ago though. But it wasn't that long ago that I caught about five fiddler sharks near the paper mill.

"I haven't seen any really big sharks up near the Bridge for donkey's years.

"When I was younger I lived on the Parramatta River and a lot of dogs used to get knocked off by sharks.

"I see kids diving off the rocks into the Shoalhaven River now, swimming with their dogs. Somebody should warn them, or at least make them aware that there are sharks here.

"I tell you what, you wouldn't get me in the river."

Mr Bird said he remembers a frightening experience fishing for bream from his boat in the river at night.

"I caught a fish and as I started to reel it in, the water just lit up with phosphorus and a five-foot school shark took my fish," he said.

"Years ago I was fishing with friends down near Comerong Island and we saw a big bronze whaler only a few feet off the bank, just cruising along."

Mr Bird said he believes the drought has allowed salt water to move further up the river, drawing the sharks in.

With more than 70 years plying the Shoalhaven River, Charlie Weir is well aware of the shark situation.

In fact, Mr Weir said he used to catch grey nurse sharks up to eight foot long as far inland as Riversdale.

"When I was about 13 years old, my dad was running a cargo boat servicing the farms along the river. He told me of a shark estimated to be about 14-feet long that was caught up off Young's Island, near Bundanon.

"You seldom see them now. You might see a three footer around Greenwell Point and up as far as Broughton Creek."

Mr Weir said large sharks aren't making their way up the river now because the waters are silting up and there are too many boats.

"For sharks the river is now like a person walking into a swarm of bees with the number of boats around."

Manager of the McDonalds Aerial Patrol, Harry Mitchell, has seen his fair share of sharks.

Flying along the coast every weekend over summer, he said one of the most popular places he and other pilots see sharks is in the mouths of the region's estuaries.

"We see sharks practically every weekend," he said.

"We often see them at the mouths of rivers, feeding and basking in the sun.

Mr Mitchell said hammerhead sharks are the most commonly seen shark in the Shoalhaven.

"Sharks go up river to pursue fish and sometimes when they're giving birth," Mr Mitchell said.

"It's an ideal environment for them to train their young to pursue food.

"In Sydney they're finding sharks up past Parramatta and I have heard people finding them up to 30kms inland near Newcastle."

A spokesperson for NSW Fisheries said some shark species, such as the bull shark, can tolerate freshwater conditions and are regular visitors to the upper reaches of our estuaries.

"Whilst shark attacks in the State's estuaries are extremely rare, all care should be taken," the spokesperson said.

"The current dry conditions mean that many saltwater species are found further up the river than normal. Sharks will follow these fish to feed.

"Whilst there are no recent records of fatal shark attacks in our rivers, swimmers should nevertheless be aware of this potential danger."