Similar artificial reefs are proposed off South Head in Sydney and off Blacksmiths Beach south of Newcastle.

The steel structures - modelled on world leading artificial reef technology used in Korea and Japan - will be the first purpose-built offshore artificial reefs (OARS) deployed off the NSW coast. The Sydney reef will be the first constructed.

Details of the proposals were released yesterday and submissions can be lodged until April 19.

Up to 40 countries around the world have artificial reefs, which were traditionally made from "waste materials" such as car bodies, tyres or shipwrecks.

Since 2005, American-designed artificial reef components, or "reef balls", have been placed in sheltered NSW waterways including Lake Macquarie, Botany Bay, St Georges Basin, Lake Conjola and Merimbula Lake.

Eight months after the reefs were created in Lake Macquarie, the abundance and diversity of fish caught by anglers was found to be as good, or better, than on naturally occurring reefs.

The reefs are being proposed by State Government agency Industry and Investment NSW and Primary Industries Minister Steve Whan said it was an exciting step in the bid to improve recreational fishing opportunities in NSW.

"This development is expected to be a boon for local communities by improving fishing opportunities, expenditure on fishing-related items and services and increased employment," Mr Whan said.

The steel structures will each measure about 12m high, 15m long and 12m wide, weighing more than 35 tonnes.

They will be sunk in water about 34m deep off Perkins Beach and spaced 200m apart in a line.

Based on a Korean design and varied to suit conditions, the structures will be built on land, transported to the proposed site by barge and lowered by crane on to the sea floor. The process is expected to take up to eight months.

Two sites off the Illawarra coast were considered for the artificial reef, including a 36sq km region to the south of Stanwell Park and extending to Bulli.

But the area off Perkins Beach and south of the Five Islands Nature Reserve was selected as the most appropriate site for the reef.

Other areas along the Illawarra coast were ruled out because of their proximity to the sewerage outfall south of Wollongong City Beach, shipping lanes into Port Kembla Harbour, existing reef shoals and shipwrecks.