A total ban has been imposed on commercial shark fishing in waters between Shark Bay and North-West Cape.
Fisheries Minister Gordon Hill said there was increasing concern that fishing pressure was depleting stocks of bronze whalers, thickskin sharks and tiger sharks in Shark Bay.
"Some of these large, continental shelf sharks take up to 30 years to reach maturity and breed only once every two years," he said.
"Sharks are an important part of the marine ecosystem and have adapted over millions of years to become the supreme predator in their environment."
Mr Hill said Fisheries Department records showed that at least 14 per cent of the shark catches in Shark Bay in the past 12 months had comprised pregnant bronze whalers.
"If we allow fishing to continue at this rate we run the risk that these sharks will simply disappear from our inshore waters, with an unknown impact on the entire food chain," he said.
"Shark fisheries elsewhere in Australia - and the world - have proved highly vulnerable to over-exploitation, because of the long breeding cycles of many species."
He said in the past year the world price of shark fin had risen from $20 a kilogram to more than $80 a kilogram.
The price jump was directly related to a shortage of shark fin on the world market caused by the collapse of most commercial shark stocks through over-fishing.
Mr Hill also said there was clear scientific evidence of a decline in southern shark stocks and that management controls on this fishery were being constantly reviewed.
"Controls on shark fishing north of Shark Bay will ensure that excess fishing effort in this fishery is not shifted further north to equally vulnerable stocks," he said.
"The new ban will also complement the recreational bag limit of four placed on sharks last year - and the Commonwealth controls on foreign shark fishing in the Australian Fishing Zone."