A central reason the seafood labeling was pushed through in 2005 was Senator Ted Stevens, Republican of Alaska, who was chairman of the powerful Senate Committee on Appropriations at the time. He went to bat for Alaska fishermen, who benefited from a provision in the law that fish and shellfish include not only country of origin but whether it was farm-raised or caught in the wild.

Today, both sides of the debate over origin labeling contend that the seafood labels support their arguments.

For instance, in March, the Food Marketing Institute, a trade organization, said seafood labeling had cost 10 times more than original estimates and failed to increase sales of American seafood.

But the United Fishermen of Alaska tell a different story, saying that origin labeling has increased demand and prices for their wild salmon. And with the current concerns over Chinese seafood, labeling of seafood gives consumers the option to buy something else, advocates say.

The push for origin labeling started in the mid-1990s, when cattle ranchers grew frustrated by the influx of imported beef, particularly from Canada, as a result of trade agreements that opened the border to imports.

The thinking behind the proposal was that, given a choice, consumers would likely choose products from the United States over imported ones, even if they cost more. But origin labeling is not just about patriotism or a desire to help American farmers. Part of its appeal is better food oversight, and some proponents of the measure have played to consumer anxiety by calling into question the safety of meat from places like Mexico, Uruguay and Canada. China exports a negligible amount of meat to the United States.

“The consumer, upon seeing the U.S.D.A. label, would naturally presume that it’s a U.S. product,” said Bill Bullard, chief executive of the Ranchers-Cattlemen Action Legal fund, United Stockgrowers of America, an organization of cattle ranchers better known as R-Calf. He said the effect for meatpackers was that “they are able to bring in a cheaper product and sell it under the reputation of the U.S. cattle industry.”