ARLINGTON, Va. — The future of the abundant rockweed growing along Maine’s coast may turn on one of our country’s oldest ideas: property rights. This week, the Supreme Judicial Court heard oral arguments over whether rockweed can be harvested from private property without owners’ consent, raising fears of overharvesting and other ecological harms.

Due to legal ambiguities that stretch back to the colonial era, no one is quite sure who owns the seaweed that grows on rocks in the area between low and high tide.

Tidal lands are private property, but the public has some rights to use it. Uncertainty in the case of rockweed has predictably led to time-consuming and expensive conflict and litigation.

But there’s a proven way to protect a valuable environmental resource like Maine’s rockweed while also reducing conflict: Define it as private property.

If landowners have clear rights to the rockweed growing along their shorelines, then they will have the ability to preserve it and incentive to ensure that any harvesting is sustainable. And in contrast to the contentious regulatory process, secure and unambiguous property rights will avoid unnecessary conflicts between property owners and rockweed harvesters, letting both focus instead on ways to conserve rockweed through compromise.

Rockweed is one of Maine’s most valuable natural resources. It is an indicator of water quality as well as a source of food, shelter and spawning habitat for a wide variety of wildlife. Rockweed is also economically valuable. The annual harvest is worth approximately $20 million, much of it used for fertilizer, animal feed or human health supplements.

As rockweed harvesting has increased, so has conflict between coastal property owners and harvesters. Worried that current harvesting is unsustainable, hundreds of coastal property owners have joined the Rockweed Coalition, an environmental group concerned about the impacts of rockweed harvesting on the coastal ecosystem. In addition, local and regional conservation organizations – including the Downeast Coastal Conservancy, Friends of Blue Hill Bay, and the Conservation Law Foundation – have lined up to express their concerns over commercial harvesting. The Rockweed Coalition has created a no-cut registry, through which coastal property owners signal that they do not approve of harvesting on their land. One of those property owners is at the center of the case currently before the Supreme Judicial Court.

Carl Ross forbids harvesting on his property. But Acadian Seaplants, one of the largest producers of marine-plant products in the world, contends it may harvest from his property without his consent. In the Maine Supreme Judicial Court, Pacific Legal Foundation and the Property and Environment Research Center recently filed an amicus brief outlining why property rights are the optimal solution to this conflict.

Property rights produce strong incentives for good stewardship. If property owners use resources unsustainably, they will directly bear the future consequences. The idea that people take better care of something they own than something owned by a stranger – or something owned by no one in particular – is not groundbreaking. There’s a reason, for instance, that people take much better care of the bathrooms in their homes than public restrooms – in the former, they know they’ll have to clean up the mess. So too with environmental resources.

But the primary reason that clear and secure property rights are the key to protecting Maine’s rockweed is that they will allow competing demands to the resource to be resolved amicably.

Property owners and harvesters could negotiate mutually beneficial contracts that would allow harvesting while protecting the long-term future of the rockweed. Market transactions would also encourage fertilizer producers or others with an interest in rockweed to uncover better information about the resource and develop new harvesting methods that can reduce environmental harms. A company that invents a less-disruptive harvesting method would have an incentive to educate property owners about the technique so that it might improve its prospects when it comes to negotiating for the right to harvest.

Relying on the political process, however, would ensure rockweed remains a continuous source of conflict. Conservationists and harvesters would jockey to steer regulation to their advantage. And the costly and time-consuming litigation would likely never end.

By clearly defining property rights, the court can put an end to the conflicts – and ensure that the rockweed ecosystem will thrive for decades to come, too.