A Superior Court judge has ruled against a Canadian rockweed harvesting company in a civil case, saying that harvesters need to obtain a landowner’s permission before they can remove the seaweed growing on private intertidal property.

The March 16 ruling by Justice Harold Stewart II, which could affect an growingexpanding industry in the state, applies to the entire coast of Maine and concludes that rockweed growing in the intertidal zone is privately owned property and is not owned by the state in trust for the public.

The Maine Department of Marine Resources and other opponents say the court’s decision will harm the $20 million rockweed harvesting industry and is almost certain to be appealed to the Maine Supreme Judicial Court.

“I’m very disappointed in the decision. I plan to continue to manage it as a fishery and will be filing an amicus brief to ensure the court has all the relevant information during the appeal process,” said Marine Resources Commissioner Patrick Keliher.

“It is important to note that in making this decision, the court made clear that it does not apply to other fishing activities that take place in the intertidal zone, such as worming, clamming or digging mussels,” Keliher said in a statement.

He said those activities remain protected under Maine law, which establishes that public trust rights in intertidal land include the right to use it for fishing, fowling and navigation.

In his ruling on the lawsuit, Stewart sided with plaintiffs Kenneth W. Ross and Carl E. Ross, who own coastal property on Cobscook Bay and Chandler Bay in Washington County, and a third plaintiff, Roque Island Gardner Homestead Corp. The Ross brothers are Calais natives and still live in Maine, according to their attorney.

Acadian Seaplants Ltd. of Dartmouth, Nova Scotia, was named as the defendant in the lawsuit.

On its website, Acadian Seaplants describes itself as a world leader in marine plant products, employing more than 350 people in eight countries.

The company says its processed rockweed is used in the manufacture of fertilizer, as well as food for people and animals. According to its website, products may include edible sea vegetables, brewing agents like Irish moss, ingredients for dietary supplements, along with cosmetics and personal care products.

Acadian Seaplants President J.P. Deveau could not be reached Tuesday, but he told Maine Public last week that the decision will be appealed to the state’s highest court.

The plaintiffs’ attorney, Gordon Smith of Portland, praised the judge’s decision and agreed with the state that it will not affect clamming or worming.

“The rights to clam, to mussel, to worm, all those are well-settled rights that will be completely unaffected by the outcome of this case,” Smith said.

Smith said that during an appeal, rockweed harvesting will be allowed to continue.

“It was a pretty comprehensive opinion by the judge. He addressed all the legal arguments that the parties were making,” he said. “Judge Stewart did a great job digging into the issues and understanding what was going on, so it was a good decision for us.”

Smith said Acadian Seaplants Ltd. will have 21 days after Stewart enters his final judgment – which had not happened as of Tuesday – to appeal the decision to the Maine Supreme Judicial Court.

Jeff Nichols, spokesman for the Maine Department of Marine Resources, said there were 134 licensed seaweed harvesters in Maine in 2016. They landed 13,977,313 pounds of seaweed, of which rockweed represented about 97 percent.

Other seaweed species that are harvested along Maine’s coast include dulse, Irish moss, kelp, nori, sea lettuce and wormweed. The overall landed value of the product – the value paid to harvesters – was $468,105 on 2016, according to Nichols.

In a 2013 report – the most recent data available – the Department of Marine Resources and Maine Sea Grant, a University of Maine research program, estimated that the overall value of rockweed, after it has been processed into retail products, is in the vicinity of $20 million per year, Nichols said.

Staff Writer Mary Pols contributed to this report.