'Simply a placebo': Shark net rollout opposed by Greens

As the NSW government prepares to roll out shark nets along much of the state's coast there are calls for the practice to be scrapped.

Board riders are seen at Coogee beach, in Sydney Source: AAP

More than 50 shark nets will be re-deployed from Newcastle to Sydney and Wollongong on Friday as winter comes to an end.

But Greens MP Justin Field says the nets are simply a placebo.

"Shark nets may make ocean-goers feel better but the evidence shows they are not effective against target sharks and don't make swimmers or surfers significantly safer," Mr Field said in a statement.

An annual report into shark nets found 373 animals were caught in the nets with more than half of them dying.

Less than 20 per cent of animals caught in the meshing were target sharks.

A spokeswoman for primary industries minister Niall Blair, however, said public safety was the government's number one priority.

"We aim to minimise the risk to swimmers and surfers from shark attacks and the amount of by-catch caught," the spokeswoman said.

The shark nets are fitted with 'dolphin pingers' and 'whale alarms' to deter the sea mammals from becoming stuck in the netting.

"Every available technology is implemented to reduce the impact on threatened species."

Shark nets are deployed along the NSW coast between September and April each year.