The global export trade in caviar, the briny eggs of sturgeon that for decades have been one of the world's most exotic and lucrative wildlife products, was abruptly ordered shut down today by the international convention that helps nations manage threatened species.

Exporting nations must "ensure that the exploitation of sturgeon stocks is commercially and environmentally sustainable over the long term," the convention's secretary general, Willem Wijnstekers, said in a statement.
Sturgeon products, legal and illegal, are thought to be worth at least several hundred million dollars each year. But scientists and managers have said for decades that the caviar industry, and the species that drive it, are in jeopardy.
The world's remaining sturgeon fisheries have all suffered from plummeting populations, caused by a combination of dam building, pollution, excessive fishing and unchecked black markets. Several localized extinctions of sturgeon stocks around the world have already occurred, and many other species, including ones in the United States, have been reduced to remnant populations.

One persistent problem in sturgeon management has been that national quotas and harvest data, which appear impressive on annual ledgers, do not account for widespread poaching. Mr. Morgan said that exporters would have to satisfy the secretariat that their fishing plans accounted for both the real size of the stocks and the total mortality from legal and illegal fishing.