Snapper stocks in South Australian coastal waters have plunged with drastic action necessary to return the fishery to sustainable levels, the state government says.

Primary Industries Minister Tim Whetstone says there has been an 87 per cent reduction in snapper stocks in Gulf St Vincent over the past five years and a 23 per cent fall in Spencer Gulf.

"This latest scientific information shows we need to implement strong restrictions across all sectors to protect the current snapper stock and enable them to recover," Whetstone said.

In December last year, the government implemented a series of closures for fishing zones and cut charter boat bag limits as an interim measure to protect snapper numbers.

It has since been consulting with the commercial, charter and recreational fishing sectors about further snapper restrictions for the upcoming summer.

Whetstone said the latest data showed the government would need to implement strong restrictions across all sectors to allow snapper stocks to recover.

"The government will take action to ensure snapper are available in the future to recreational, charter and seafood lovers alike," he said.

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