The much-anticipated annual mullet run on the east coast of Australia is in full swing now that the cold snap needed to flush the fish from estuaries into the sea to spawn has finally hit the New South Wales mid-north coast.

The fish usually appear around Easter time and are present through to the end of June, but it is thought the late summer delayed this year's run.

The Bull family have been hauling mullet off the mid-north coast for five generations.

Commercial fisherman Wade Bull with his daughter near the mouth of the Hastings River in Port Macquarie. ( ABC Mid North Coast: Luisa Rubbo )

Wade Bull and his sons work between the two river mouths of the Hastings River in Port Macquarie and the Macleay, around Kempsey.

Once the fish are pulled out, fish buyers load them into cages, put on them on ice and take them to Kempsey where they are shipped off to the larger fish sales and distribution companies. Much of the catch is exported to south-east Asian markets.

"Everything you see on the mullet is used. Nothing is wasted. Scales, eyes, the whole lot. Everything is used, " Mr Bull said.

The Bull family with friends on the mullet run near Port Macquarie. ( ABC News: Luisa Rubbo )

Bull sharks and dolphins

Family friend Pelham Wooderson has been hauling mullet for more than 60 years, mainly around South West Rocks and Crescent Head. This was his first time in Port Macquarie.

"It's the excitement of the net going around and the fish and everything else," Mr Wooderson said.

"It's cool but it's not too cold and when you catch fish in the morning you can dry out in the afternoon and recover a bit.

"But if you get fish at night and you're working into the night it's not a nice time to be on the beach.

Pelham Wooderson has been hauling mullet for more than 60-years. ( ABC Mid North Coast: Luisa Rubbo )

"They're actually a little bit easier to catch at night with the spotlights and everything. It seems to dull them down a little bit and they are a bit easier to catch."

Mr Wooderson said that sometimes bull sharks would swim in behind the net and also dolphins on occasion.

Environmental impact assessments

Lee Burdett, a supervising fisheries officer with the NSW Department of Primary Industries, said fisheries off NSW had undergone environmental impact assessments to make sure they were sustainable.

Ms Burdett said the mullet run often resulted in very large catches that could be confronting for members of the public unfamiliar with the spectacle.

She said the nets were specifically designed for mullet and smaller species could pass through.

"What is caught commercially is a very small component of the total population of mullet," Ms Burdett said.

"There are still plenty of fish in the sea to continue spawning and that is seen by the quantities of mullet that run to sea every year.

"If the fishery wasn't sustainable then over time those quantities would be reducing and reducing — we're definitely not seeing that."

The fish are packed into cages before being taken away for sale and distribution. ( ABC Mid North Coast: Luisa Rubbo )

'A good set of eyes'

While much of the knowledge has been learned over five generations — technology is also playing a part.

Mr Bull said drones were used to spot the shoals from the air.

"Usually we would've have to walk through bush tracks and back-tracks and climb over rocks and down into places you wouldn't think you could get to just try to find them, Mr Bull said.

He said good vision was also useful.

"Not everyone can see them. My father and my uncles are really good. They don't miss a fish.

"They have got a good set of eyes on them. I think it's been handed down."