NEW ORLEANS >> A federal judge in New Orleans has thrown out the National Oceanic and Atmospheric Administration’s rules for fish farms in the Gulf of Mexico, saying the agency lacked authority to make them.

Tuesday’s ruling halts a plan that would have allowed, “for the first time, industrial aquaculture offshore in U.S. federal waters,” according to the Center for Food Safety , which sued NOAA on behalf of what U.S. District Judge Jane Triche Milazzo described as “a bevy of special interest groups representing both food safety advocates and Gulf fishermen.”

The government considers fish farming, including that on the open sea, to be “vital for supporting our nation’s seafood production, year-round jobs, rebuilding protected species and habitats, and enhancing coastal resilience.” Opponents say huge numbers of fish confined in nets out in the ocean could hurt ocean health and native fish stocks, and the farms would drive down prices and devastate commercial fishing communities.

“It’s a landmark decision,” George Kimbrell, lead counsel for the Center for Food Safety, said in a telephone interview from San Francisco.

“NOAA wanted to do this sort of industrial permitting not just in the Gulf of Mexico but in the Pacific and along the Atlantic coast,” he said.

The agency was working on rules for waters around Hawaii and other Pacific islands.

NOAA is considering whether to appeal the ruling handed down Tuesday, it said in an emailed statement.

The decision doesn’t forbid aquaculture, the statement emailed by spokeswoman Jennie Lyons noted. “NOAA remains committed to expanding the social, environmental, and economic benefits of sustainable marine aquaculture in the U.S.” it said.

“Given conflicting court decisions and the desire for regulatory certainty, NOAA supports congressional efforts to clarify the agency’s statutory authority to regulate aquaculture,” the statement said.

Kimbrell said the only related ruling allowed NOAA to regulate a single boat towing a fish pen in the Pacific.

A bill by Republican U.S. Sen. Roger Wicker of Mississippi is now the open-water industry’s only way forward, plaintiff and land-based aquaculture advocate Recirculating Farms Coalition, which is fighting the legislation, said in a news release.

Wicker’s bill notes that the U.S. imports more than 90 percent of its seafood and about half of that comes from aquaculture. “The United States, as a result, runs a substantial trade deficit in seafood,” it states. The bill would create an office of marine aquaculture within NOAA’s National Marine Fisheries Service, to coordinate aquaculture regulation, science, outreach and related international issues.

Kimbrell said NOAA put forward its rules under the existing fisheries law, called the Magnuson-Stevens Act, after bills like Wicker’s had failed to pass from about 2002 through 2008.

The agency contended that it could regulate harvesting of farmed fish because Magnuson-Stevens gives it authority over fishing, and its definitions of fishing include harvesting fish.

“We said, no, that’s crazy. … Growing fish in a net pen just not the same as going out in a boat and catching them,” Kimbrell said.

Both sides had asked for a summary judgment, without trial.

Milazzo said nothing in the law’s purpose or findings mentions management of fish as farmed crops. Three brief references to aquaculture make it clear that Congress was aware of the field, she noted.

“Further,” she wrote, “Plaintiffs point out various ways in which the (law) as a whole is nonsensical when applied to aquaculture.”

Because the law didn’t authorize the regulations, Milazzo wrote, she doesn’t have to rule on challenges that NOAA “failed to properly consider a litany of environmental problems” presented by open-water aquaculture.

Kimbrell said environmental problems include pollution from the pesticides, fungicides, antibiotics and other chemicals needed to keep fish healthy in such small quarters. In addition, he said, about 20 percent of farmed fish escape, competing with wild fish for food and habitat.