"No way in the world."

Based at Greenwell Point, he and his brother Barry have been working the river system as oyster farmers for 54 years. They've seen sharks and heard enough about them to make them swear off taking the plunge.

One encounter was right out the front of their shed, which sits on the banks of the Crookhaven River, which drains the Shoalhaven out to the sea.

The sharks were chasing fish. A nearby boat builder also spotted them as they cruised past his jetty.

"As the sharks went back he raced up to the house and got the shotgun and he was shooting at them as they were going past," Brian says.

He recalls being working on the water and hearing splashes too large to be ordinary fish.

"You're working away and next minute, especially down at the mouth of the river where we used to put plastic slats out to catch the baby oysters, and next minute there'd be a massive splash."

Their lives on the river have also meant the Allen brothers are tuned into the fishers' telegraph, often buzzing with stories of shark encounters. There were reports of bull sharks caught just off Greenwell Point last year and up past Berry's Canal, dug out by hand in 1822 to make the Shoalhaven River navigable by connecting it to the Crookhaven.

"A very good friend of mine - he's sadly departed now - he'd dived all over the world and he said, 'Brian, there's one place I would never ever swim and that's up the Shoalhaven'."

When the Princes Highway used to run through the centre of Nowra, Brian recalls, there was a landmark locals all knew.

"There was a fisherman there and he had bull sharks' jaws nailed on the garage door of his shed. He caught them in the nets all in the Shoalhaven up past Greys Beach."

Not everyone shares the Allens' concern about sharks.

Tony Emery has lived by the river - and spends a lot of time in it - at a place called Wogamia, 20-odd kilometres upstream from Greenwell Point..

"The last shark sighting here was during a big drought at the end of the war. My dad Foster had taken some cows down to the river for a dip. He took a dip himself, when he saw a shark. He got out of the water quick smart."

Emery says the much more immediate threat was reckless wakeboarding boats.

World-renowned underwater photographer and diver Attila Kaszo has no qualms about venturing into the depths of the river.

"I've never seen a bull shark in it but that's not to say they aren't there," he says. "And I've dived the Shoalhaven a few times - even a couple of night dives photographing bass."

Seeing sharks is not the problem, says Kaszo. It's not seeing them when you want to photograph them. The photographer's most famous shark encounter, one which earned him headlines around the world, was in 2015, when he was the first person to photograph an elusive thresher shark giving birth to a pup. But his interaction with a bull shark in waters off Fiji was probably the most terrifying.

He was filming a group of them feeding on a bait below when a large one changed direction.

"For some reason it came to the surface and headed straight for me. I hit it in the eye with my camera rig and it snapped the GoPro off off the top of the housing.

"Bull sharks are blind as bats. They use their mouths to investigate. Those mouths are huge and full of teeth."

Biologist Dr Jane Elek lives by the Moruya River and is heavily involved in the Nature Coast community group. She's more worried about warm waters carrying tropical stingers into our rivers than sharks. She recently encountered a jimble in the Clyde River near Batemans Bay. A small jellyfish, the jimble can deliver a nasty sting, which Elek says is much worse than that of a bluebottle.

"And I think aggressive seals in the Wagonga Inlet at Narooma are more likely to bite you than a shark."

Clyde River oyster farmer John Yiannis has seen turtles, seals and dolphins upstream.

"We even had a sunfish between our racks and had to shepherd it out. But I've never seen a shark. Not once."

That's not to say shark attacks do not happen on the NSW South Coast, some of them fatal.

In April 2014, a 63-year-old woman was killed while swimming off Tathra. In 2016, Brett Connellan was attacked while surfing off Bombo Beach in Kiama. And in 2021, a woman on an early morning swim was attacked at Merimbula on the Far South Coast.

Dr Elek offers some context: "Do people not drive anywhere because they might have an accident?"

Many more people have died on roads getting to our rivers and beaches than have lost their lives to sharks.