Let’s face it: our taste for seafood brings a whole host of environmental problems. Overfishing affects marine ecosystems, while lost fishing equipment contributes to ten percent of the plastic in the ocean. Not to mention, pollution from fish farms flows into the ocean, leading to destructive algae blooms. Land-based fish farming is an alternative to open water fishing. Because fish grow in closed tanks, there’s no equipment to lose, and waste won’t flow into our ocean’s ecosystem.
In Umeå, in northern Sweden, scientists are developing a circular land-based fish farm where different species cohabit, so that one fish breed can ingest another’s waste. What’s more, excess heat from Umeå’s power plant heats the fish farm, reducing its heating emissions. The EU-funded project will begin in spring 2026 as a collaboration between Umeå Municipality, Umeå Energi, RISE and the Umeå Plant Science Centre at Umeå University. The team aims to establish a pilot facility with the potential to scale to a larger facility within a year.
Utilising every nutrient by mimicking our natural ecosystem
The fish farm will grow shrimp and tropical fish such as Tilapia, breeding them together using IMTA (Integrated Multi-Trophic Aquaculture) principles. By mimicking our natural ecosystem, this method of circular fish farming means every nutrient is utilised, and waste becomes a valuable resource. Meanwhile, the heat from Umeå’s power plant is captured as both air and liquid, then transferred via district heating systems to heat the fish farm.
Heat reuse: from power plants to data centres
It’s not just power plants that can be used to heat fish farms. Servers in data centres release a lot of heat, which can be captured and reused in fish farms, swimming pools or residential heating. Find out more about the potential of data centre heat reuse in our explainer article.
Another key principle of the project is to “replace imported food with local production,” according to Hans Lindberg, Chair of the Municipal Executive Committee. “[This] strengthens our self-sufficiency, increases resilience and reduces climate emissions,” he adds. In an interview with RESET, Olivier Keech, Associate Professor at Umeå University in the Department of Plant Physiology, said that the project aims to “produce a self-sustainable system”. “Sweden imports 70 percent of fresh produce consumed in the country,” Keech explained. “If a crisis arises, Sweden is very vulnerable in terms of food availability, particularly with such a challenging climate, for example, long winters and shorter growing seasons.”
By producing more fish locally, the project will also reduce Sweden’s carbon footprint by minimising the need to import fish from distant countries. With the EU only able to produce 37.5 percent of the fish it consumes, according to Seas At Risk, Umeå’s pilot could hold valuable lessons for other EU countries.
The potential for sustainable fish farming at scale
For now, the project in Umeå is optimising its techniques. “We are doing mathematical modelling, which provides different strategies for improvements, both for the sustainability and economics of the project,” Keech said. Their next steps? “Continuing to test and model via different pilot projects, and keep optimising the biofloc, the feeding strategy, the design of the system.”
While the aim is to eventually scale, Keech tells us that “what works in a small scale is not directly transferable to a large scale. Scaling up is unfortunately not linear.” However, Umeå has laid a strong foundation for a new kind of circular aquaculture system. As Keech puts it, “We have the surplus heat, the research environment and the partnerships needed to scale up the farming in a real, sustainable way.”
However, even if we see more farm-raised seafood on our shelves in the coming years, this will never be enough to meet the current high demand. Keeping our fish consumption to a minimum will undoubtedly remain crucial to preserving our marine ecosystems.
