The Bahamas has banned shark fishing in its waters and prohibited the sale, import and export of shark products.
The new law will effectively turn all 630,000 sq km (243,000 square miles) of the nation's territorial waters into a shark sanctuary.
The ban was approved by Agriculture Minister Larry Cartwright in the capital, Nassau, on Tuesday.
The archipelago joins Honduras, the Maldives and Palau in outlawing shark fishing.
The government also increased shark-fishing fines from $3,000 (£1,900) to $5,000.
Sharks are considered at risk due to demand for their fins in Chinese cuisine - some 73 million of the sea predators are killed each year, environmentalists say.
In 1993 the Bahamas banned long-line fishing, which limited shark fishing and protected 40 species of sharks inhabiting its waters.
But shark fishing was not banned outright, and when a local seafood company announced last year that it planned to export shark meat and fins to Hong Kong, activists called for a new law to be introduced.
Environmentalists welcomed the ban. Neil McKinney, president of the Bahamas National Trust, which manages the country's resources, said sharks played an extremely important role in balancing the ecosystem.
"They desperately need protection if we're not going to drive them to extinction," AFP news agency quoted him as saying.
Tourism is a major industry in the Bahamas, and shark-diving earns it $80m a year in revenue, according to a recent survey.
The country's main island, New Providence, is home to Jaws Beach, where one of the Jaws films was shot. Last year, the remains of a boatman who had disappeared off the beach were found in the stomach of a tiger shark caught by an investment banker.
The US-based Pew Environment Group said each reef shark brought some $250,000 to the archipelago's economy.
Deputy Prime Minister Brent Symonette said he did not think the ban would affect relations with China, which has increased trade with the Bahamas in recent years.
"This is in keeping with the government's commitment to pursue conservation policies and strategies in order to safeguard the marine and terrestrial environment," the Associated Press quoted him as saying.