More than an hour south of Oslo, near the mouth of the Glomma River, hundreds of thousands of salmon swim in cold, dark depths.
They are not in the ocean or in the river. These salmon survive in enormous circular pools at a land-based fish farm in the former whaling town of Fredrikstad, where they are raised from juveniles to full-size adults.
Roger Fredriksen, the production manager at Fredrikstad Seafoods, moved to southern Norway to join the company five years ago.
He says that it has been a really exciting journey because this is totally new.
Fredriksen is not alone. Between 2008 and 2018, employment in Norway's seafood sector grew by 10 per cent to reach 30,000.
The Scandinavian country is the second-biggest exporter of fish after China, with sales increasing by 72 per cent between 2008 and 2018. By 2050, the country plans to produce 5 million metric tons of salmon and trout a year, nearly five times its current volume.
Aquaculture accounts for 52 percent of the seafood eaten around the world and has risen more than 500 percent since 1990. Its carbon footprint is low – accounting for less than 0.5 per cent of greenhouse gas emissions in 2017 compared to 14.5 per cent for livestock – it can cause serious damage to marine environments. Among the problems are chemical pollution, escaping fish, and the spread of diseases and parasites.
Land-based aquaculture is more sustainable and less harmful to the environment than conventional fishing and sea-based fish farming. Some people think it's the future of sustainable seafood because of its smaller carbon footprint and potential proximity to markets.
Rob Fletcher, senior editor at The Fish Site, says that people see it as the future. The cost of producing them at sea is going to go up. With these land-based RAS recirculating aquaculture systems you can in theory have them anywhere, there is limited availability of where to grow them at sea. You can have them in the Middle East, you can have them in Florida, you can have them in Norway. RAS technology, of the kind used in Fredrikstad, provides a controlled environment for the fish. The water in which they swim is passing through a filter that cleans and recycles it into the tank system without the waste, uneaten feed and ammonia naturally produced by the fish.
The company uses saltwater from the nearby Glomma, which is pumped in and cooled before it enters the RAS. Salmon are acquired as smolt-juvenile fish that would be preparing to migrate from rivers to the sea and raised in circular pools in two warehouse facilities.
The fish, about 280,000 in total, spend their entire lives in these tanks without ever going to the ocean, a practice that is still being tested and tried in the industry, Fletcher says.
Fredrikstad chief executive Bernt-Olav Rttingsnes says salmon is typically cultured for two years. They are then harvested, processed and transported by truck to customers in Oslo and neighbouring countries, all within a 12 to 24 hour radius.
R ttingsnes says that we don't think that land-based aquaculture is something you should place very far away from the market.
While some see land-based aquafarms and RAS as a sustainable way forward, critics worry about the amount of energy and resources needed, the wellbeing of the fish, and the feed being linked to deforestation.
In Norway, 93 per cent of the electricity generated by hydro power comes from renewable energy, but in areas where renewable energy is less accessible, such as in parts of the Middle East and the US, these energy-intensive facilities can have a larger carbon footprint, Fletcher points out.
Rttingsnes does not see this as a problem for Fredrikstad. He acknowledges that there are pluses and minuses, with land-based energy consumption being a minus for land-based. He adds that putting the production close to the market makes up for it.
Nordic Aquafarms, the parent company of Fredrikstad Seafoods, also has a plant in Denmark that produces yellowtail kingfish, and is planning two new farms in the US, Maine and California. It intends to buy renewable energy or install solar panels to reduce the carbon footprint.
Green party MP Ramus Hansson, who sits on the business and industry committee in Norway s parliament, agrees that land-based aquaculture has the potential to be sustainable. He adds that it is important to consider what the fish are fed because the aquaculture industry as a whole is so big.
Feed is imported from Brazil and there are some well-known issues related to deforestation, he explains. There is no basis for calling the feeding of the industry sustainable at this stage. Rttingsnes says Fredrikstad's feed comes from Europe and emphasises that energy consumption and fish welfare are also important to the company.
Fish farming accounts for only a small portion of global aquaculture, according to land-based fish farming. There is a chance that this will change quickly due to a skills shortage and the difficulty of finding sites with the necessary water and transport infrastructure, but the long-term outlook is promising.