The duties were generally lower than preliminary levels announced earlier this year, with the notable exception of one Brazilian company, Norte Pesca, which still faces a duty of 67.80 per cent, the Commerce Department said.

Commerce set duties for Thailand, the largest of the four suppliers, ranging from 5.79 per cent to 6.82 per cent, down from preliminary levels of 5.56 per cent to 10.25 per cent in July.

It also scaled back duties for India and Ecuador and for individual Brazilian exporters.

Eddie Gordon, president of the Southern Shrimp Alliance, which represents shrimpers in eight southern US states, said the reduced duties would still help the industry survive.

US shrimp fishermen and farmers use the most advanced technology and are very efficient producers of shrimp, but some of our trading partners have been cheating and causing US businesses to close and thousands of Americans to lose their jobs," Gordon said in a statement.

A coalition of seafood distributors and restaurateurs, called the duties and unwelcome tax on America's most popular seafood. They also said the duties could be overturned by the World Trade Organization.

last week, Thailand challenged preliminary US duty levels at the World Trade Organization on the grounds that the methodology used by the United States to determining the level of "Dumping" violated international trade rules.

Brazil, which faces final duties ranging from 9.69 per cent to nearly 68 per cent, has also threatened a WTO complaint.

At issue is a controversial practice called "zeroing," in which the Commerce Department considers only sales made below "fair market value" in calculating anti-dumping duties. Any sales made at prices above fair market value are ignored.

The WTO has already ruled against the United States in one case where the practice was used. But James Jochum, assistant secretary of Commerce for import administration, told reporters that decision did not require the United States to abandon zeroing in every anti-dumping case it considers.