This post originally appeared in The Ellsworth American.
The Maine coast has long sustained thriving ecosystems, natural beauty and generations of fishers and wild harvesters. These same waters now support windjammer sailing, coastal hiking and whale-watching tours. But quietly, Maine state officials are clearing a regulatory path for a potentially damaging industry: industrial fish farming. While other regions are closing salmon farms due to their environmental toll, Maine has become one of the last remaining viable areas in the United States for their expansion.
An alluring pitch for oceanfront fish farming is that it generates reliable jobs by producing sustainable and efficient food without depleting the ocean. Scientists use standard metrics to evaluate these claims, including the “fish-in, fish-out” ratio, which shows how many pounds of wild fish inputs, rendered into fish meal and oil, that it can take to produce a single pound of farmed fish output.
The industry claims that its use of wild fish feed is dropping rapidly. But my colleagues and I pored over the data, and our published research found that rates are still stubbornly high. Producing 1 pound of farmed salmon can demand 3 pounds of wild-caught fish or more, rendered into feed.
To bring wild fish feed usage down, the industry has partially shifted to crops like soy and corn. But this just plays a shell game, moving harmful impacts from ocean to land. Between 1997 and 2017, as the industry reported drops in wild fish use, there was a five-fold increase in the use of land-based feed crops, leading to deforestation in places like the Amazon rainforest. Shifting feeds from oceans to farmland requires more freshwater irrigation and pesticides and generates groundwater pollution and greenhouse gas emissions.
The expansion of large-scale aquaculture in Maine isn’t being driven by local families, but by international corporations. Permissive Maine state rules allow companies to lock in 20-year leases covering up to 1,000 acres. As of 2025, the state eliminated the requirement for public hearings before approving long-term lease renewals. Meanwhile, state environmental permits allow for large amounts of waste to flush out of these open net pens and into the ocean. Furthermore, the state no longer requires hydrodynamic modeling for these renewals, which is an inexpensive and robust way to verify whether the tides and currents actually flush wastes further out to sea.
Industrial net-pens can pollute and sterilize Maine’s wild ocean fronts. These sprawling operations dump waste, sea lice, disease pathogens, pesticides and antibiotics into public waters. Even if waste effluent does largely flush out from one water body, it can harm marine life further out at sea. Net-pen arrays also obstruct and privatize public water. Several cages per farm, each holding 100,000 or more fish, are strapped to concrete slabs on the seabed. Mooring cables span outward from pens, obstructing boat navigation routes and making corridors for endangered North Atlantic right whales more dangerous. Industrial aquaculture poses risks to the Gulf of Maine’s rich but already struggling food web, the primary biological engine that supports whales, sustains working waterfronts and anchors Maine’s entire coastal economy.
All of these concerns are galvanizing coastal towns, from Washington County to the Midcoast, to wield their constitutional “home rule” authority to pass local ordinances and moratoria where the state won’t exercise caution. Maine communities want to determine for themselves how to balance the potential for jobs with the myriad risks of developing fish farms. As a researcher, I know that these important decisions require transparent data with careful analysis. Maine is currently lacking much of the data needed, but state authorities are trying to further exempt the industry from showing its “homework,” leaving us unable to track resource use and wastes.
Research shows that the risks are real, both across the Maine coast and far abroad. Due to fish farming’s large feed requirements, demand has reached as far as West Africa, where feed processing plants strip sardines from local markets, and even Antarctica, where industrial fleets are catching krill in record numbers, depriving struggling whale populations.
Maine’s coastal waters are a public trust. Working waterfronts need more transparent science, conducted by independent researchers who are not funded by that very industry, to weigh economic growth against large environmental risks. It’s only with this science that Maine has the information needed to set its own course.
Matthew Hayek is an Associate Professor of Environmental Studies and the Faculty Coordinator of the Food Impact Program at New York University.