he state of Maine once had one of North America’s great wild Atlantic salmon runs, now destroyed by polluting paper, textile, and saw mills and the construction of hundreds of dams. It was replaced with open-pen salmon farming, but that created new problems. Now a new kind of salmon farming – inland rather than offshore – is supposed to solve all those problems and more, providing jobs and putting an end to escaped fish polluting the remaining wild stocks. One of these land-based salmon farms is planned for Bucksport, a down-on-its-luck industrial town of 5,000 people on the estuary of the Penobscot, a struggling wild salmon river. Another is intended for Belfast, population 6,700, further south on scenic Penobscot Bay. As in much of coastal Maine, in the north-eastern corner of the US, this historic town has become a haven for affluent incomers, who buy summer homes and attract shops and boutiques. Until 2014, Bucksport was home to the Verso paper mill. When it closed about 500 people lost their jobs, and the town was left with an ugly, smoke-stacked industrial site. Like most paper mills, it was extremely polluting. The fish farm, part of a Maine company called Whole Oceans, has been welcomed, the local view being that it would be less polluting than a paper mill and might also replace some of the lost jobs. “I’m not sure we could do any better than what we’re doing. If there was [something], I don’t know what it would be,” says town manager Sue Lessard. Meanwhile, Nordic Aquafarms, a Scandinavian company with two farms in Denmark, one in Norway and plans for another in northern California, has chosen Belfast for its site. A more ambitious project than that planned for Bucksport, the company hopes to create the second largest such farm in the world. Welcomed by officials for its potential contribution to the town’s economy, there has been opposition from some local people wary of the effects of industry on their quaint community. “Its too big,” said John Krueger, a resident and activist who opposes the project. “It sounds great. I don’t know if you can pull it off. We are doing stuff that has never really been done before.” Factory-farmed fish Land-based farming using an RAS – recirculating aquaculture system – raises the fish with no exposure to the ocean other than fast-flowing, temperature-controlled water which is pumped in and out of the fish tanks round the clock. There are also freshwater tanks for the young stock. In the case of the Belfast project, these would be housed in several two-storey buildings surrounded by greenery, which are being built on the town’s outskirts. Erik Heim, president of Nordic Aquafarms and one of the world’s most experienced operators in the sector, said that while many problems have been overcome he is ready for the unpredictable. “It is an emerging industry and there is a learning curve.” Many environmentalists, including the Maine chapter of the Atlantic Salmon Federation, an international conservation group, have welcomed the new technology because of concerns about traditional open-pen salmon farming. Open-pen salmon farming started in Norway in the 1970s as an alternative to the diminishing stocks of wild Atlantic salmon. This was salmon that claimed to be sustainable, derived from the sea, very energy efficient and a high quality, inexpensive protein. But problems quickly emerged, such as how to deal with huge quantities of fish waste. Nor was it sustainable because the salmon were fed fishmeal, ground-up catch from the most destructive factory trawlers in the northern seas. The farmers have struggled to reduce the fishmeal content. One substitute was soy, but even GM-free soy from Brazil isn’t sustainable when farmed in cleared rainforest. The two biggest problems are escaping fish and sea lice. Farmed salmon, selectively bred for fast growth, lack the survival skills of wild salmon and when they interbreed they weaken the wild stock. There are now many more farmed than wild salmon in the Atlantic. Norwegian scientists estimate that there only about 1.5 million wild Atlantic salmon left in the world, 500,000 of them in Norway. According to the Norwegian Institute for Nature Research, there are about 400 million farmed salmon in Norway alone. Even a small percentage of these escaping presents a real threat. Millions of salmon in close quarters are to sea lice what a honey pot is to ants. These small crustaceans are a problem for the farmers and the wild fish population. A few lice are to be expected, but pens containing millions of trapped salmon attract them like a deadly plague. Farmers have looked for solutions – including raising lice-eating fish. But they don’t seem to eat enough of them. Although land-based fish farming does not solve all the problems faced by the industry, it does remove the issues of escapes and sea lice. Soaring climate emissions Nordic Aquafarms plans to harvest 32,000 tons of salmon in its Belfast operation, and while it has not completely resolved the feed problem, it hopes to use algae oil as a source of nutrition. Heim claims the Belfast plant will clean water to 99%. Some local people doubt this figure but government regulators have accepted it. Different RAS plants can have various ways of recycling their waste. Some use it for hydroponic farming but in Belfast the plan is to sell it to fertiliser companies and as biogas to energy suppliers. Norwegian open-pen farmers have traditionally resisted RAS technology. Indeed, Heim says the biggest obstacle faced by his company so far was to obtain a permit for its RAS facility in Norway, where open-pen farming is a major industry. Pen farmers have always feared that moving to land – and into indoor tanks – would open them up to the same criticism animal rights and environmental activists aim at the meat industry. But the primary objection in Norway and in Maine is that an RAS farm takes a low-energy industry and substantially increases its carbon footprint. An open-pen farm uses the natural force of the ocean, whereas an RAS is continuously operating pumps and regulating temperature. “Why so large?” asks Krueger, who like other local people points out that Maine is officially committed to lowering carbon emissions. The climate crisis has raised water temperatures, affecting the spawning and survival rates of wild salmon, but open-pen farming is also threatened by rising water temperatures. Heim believes the warming of the oceans will eventually drive salmon farming on to land where the temperature can be controlled. He acknowledges that he will burn more fuel than open pens, but hopes to compensate by only supplying fish to local markets and not flying it around the world like the pen farmers sometimes do. Belfast is within trucking distance of the major markets of Boston and New York. “We want to be where the consumer is,” says Heim, but it remains to be seen how this will work with the large-scale production he is planning. The question remains, how can the solution be a technology that increases carbon emissions? Sign up for the Animals farmed monthly update to get a roundup of the best farming and food stories across the world and keep up with our investigations. You can send us your stories and thoughts at animalsfarmed@theguardian.com