That was before everyone wanted a piece of Connemara, a region on Ireland’s west coast that includes the Kinnelly Islands and Kilkieran Bay and is one of the most pristine areas in the world for seaweed. Now, a Canadian corporation wants greater control of that seaweed.

The company, Acadian Seaplants, took over seaweed processing in the region about a decade ago. As the value of the algae surges, Acadian is also seeking exclusive rights to harvest it along much of the shoreline, where people have done so informally for generations.

Experts say the company’s sweeping proposal risks the stability of the marine habitat and the livelihoods of traditional harvesters like Mr. Dundass.

“You could be in trouble,” he said, slicing the seaweed from the rocks. “We just don’t know.”

From ‘Niche Product’ to Powerhouse

For centuries, seaweed has been part of the fabric of life in Connemara. With its small population, minimal runoff and proximity to the Gulf Stream, the region’s craggy coastline is perhaps one of the most fertile environments in the world for seaweeds like Ascophyllum nodosum, or Asco, a stringy brown algae with air-filled bubbles.

The economic potential of Connemara’s seaweed processing was long contained to Kilkieran Bay, where the Irish state began operating the Arramara Teoranta plant in 1949. From one slipway, harvesters across Connemara could collect, package and sell their bales as far away as Scotland or as close as Kerry or Galway City, where farmers bought the seaweed to fertilize their fields.

But in recent years, Western industry discovered what Connemara already knew: Seaweed is nutrient-rich, all-natural and — in the modern wellness boom — eminently marketable.

“Seaweeds have never been in the spotlight like it is today, globally,” said Maggie M. Reddy, a marine biologist who specializes in seaweed studies at the University of Galway. “It’s exploded from a niche product to an economic powerhouse.”

In the midst of this, in 2014, the Irish state sold Arramara Teoranta to Acadian, which supplies seaweed to the global fertilizer and biostimulant industries. According to local government documents, obtained by The New York Times, officials selected Acadian over bids by two other companies, including an Irish one. The sale, for an undisclosed amount and subject to a confidentiality clause over its terms, prompted pushback from local harvesters.

Some improvements were immediate: The price of the harvesters’ seaweed went up, and the company upgraded the aging factory.

But Acadian’s arrival also brought an abrupt shift. Arramara Teoranta, long a key supplier across the region, was suddenly owned by a global competitor that had an effective monopoly over processing. An urgent question emerged: Who would cash in on Connemara’s seaweed?

Despite initial promises that it would continue to supply local companies with seaweed, Acadian stopped doing so in 2022. The company applied for exclusive harvesting rights across much of the public foreshore in County Galway last year. Guided by the knowledge of its local suppliers, Acadian had quietly mapped every inch of Connemara’s coast, identifying areas where harvesting rights had never been formally claimed.

The company said it was simply following maritime law that had been ignored.

But in Connemara, which has dealt with centuries of outside forces — British conquest, the Great Famine and, more recently, a wave of wealthy, seasonal transplants — it was seen as a profound betrayal.

A Fight Over Land and Labor

Residents like Mr. Dundass have traditionally navigated the foreshore with gentlemen’s agreements and intuition. Neighbors handled harvesting rights with good faith, cash and mutual trust, part of a collective need to protect a shared resource.

Acadian’s application for licenses wrenched South Connemara into a bureaucracy that had been bypassed in favor of these congenial arrangements. Irish law requires a maritime usage license for the harvesting of seaweed on any foreshore, including private land. Few had gone through the arduous, expensive process of obtaining one, nor had they registered their territorial claims with the state.

If Acadian’s exclusive licenses are approved, locals would lose their right to harvest on that land unless they sold to the company. If they chose to harvest or sell elsewhere, the state would require them to obtain their own license — which can cost thousands of dollars — by 2028.

“These things are very difficult for people who have been used to doing things their own way their whole life,” said Jim Keogh, the Europe director for Arramara. “There is a clash.”