Colemann Pat Dundass, 78, has harvested seaweed on the Kinnelly Islands in Connemara, Ireland, for decades, following his father's tradition. He notes the seaweed hasn't grown back properly since it was cut incorrectly years ago. Connemara's pristine coastline, including Kilkieran Bay, is one of the world's most fertile areas for Ascophyllum nodosum. For generations, locals harvested informally, selling to the state-owned Arramara Teoranta plant since 1949.

In 2014, the Irish state sold Arramara Teoranta to Canadian corporation Acadian Seaplants for an undisclosed amount. While Acadian initially raised prices and upgraded the factory, it gained an effective processing monopoly. In 2022, Acadian stopped supplying local companies and applied for exclusive harvesting rights across much of County Galway's public foreshore. The company mapped the entire coastline, identifying unclaimed harvesting areas.

Marine biologist Maggie M. Reddy of the University of Galway says seaweed has exploded from a niche product to a global economic powerhouse. Traditional harvesters like Mr. Dundass fear Acadian's sweeping proposal risks marine habitat stability and their livelihoods. "You could be in trouble," Mr. Dundass said. "We just don't know."