Welfare and Energy Use in Land-Based RAS Production
Aquaculture—especially open-water salmon farming—has long faced criticism from environmental groups across the regions where it operates. This pressure has even contributed to production bans in countries such as the United States and Canada.
In response, many have argued that salmon farming should transition onto land through Recirculation Aquaculture Systems (RAS). These systems drastically reduce water use, allow nearly complete recycling, and enable internal control and treatment of waste—making them one of the most sustainable protein-production systems available.
No one disputes RAS’s water-use efficiency. It recycles more than 99% of water and uses only a fraction of what is required for most other animal-protein industries.
However, new concerns are now emerging. Critics of land-based farming raise issues around fish welfare and high energy consumption, questioning whether RAS is as sustainable as previously believed.
Fish Welfare
Fish welfare is an important and legitimate topic. One of the key indicators is stocking density, typically measured as kg of fish per m3 of water volume. Higher densities increase output up to a point, but above the threshold fish become stressed, and growth performance declines.
Early RAS projects projected extremely high densities—sometimes 100 kg/m³ or more. Research and practical experience have since shown that these levels are counterproductive and harmful to welfare.
Current recommended stocking densities for salmon grow-out:
- Norwegian Directorate of Fisheries (RAS): ~70–80 kg/m³
- Scottish RAS operators (e.g., Bakkafrost, Mowi post-smolt): 60–75 kg/m³
- EFSA Scientific Opinion (2023): <80 kg/m³ for sustained welfare
- RSPCA Assured / ASC: typically ≤80 kg/m³
Future RAS developments are expected to align with these evidence-based density limits. When facilities adopt responsible stocking levels and reliable technology, both welfare and financial viability are maintained—leaving welfare-based criticism with little foundation.
Energy Consumption in RAS
RAS does consume energy, due to processes such as pumping, oxygenation, and internal waste treatment. However, this energy use exists because RAS systems internalize environmental management that other industries release into the environment.
RAS is not energy-hungry because it is inefficient—it is energy-hungry because it is responsible.
How RAS Energy Use Compares to Other Industries
| Industry / Sector | Energy Use (kWh/kg product) | Notes |
|---|---|---|
| Recirculating Aquaculture (RAS) | 5–10 | Internalized waste treatment. |
| Dairy processing | 5–15 | Pasteurization and refrigeration are major loads. |
| Beverage production | 2–8 | Water treatment, packaging, cooling. |
| Poultry / pork processing | 3–10 | Chilling, transport, waste management. |
| Textile manufacturing | 20–60 | Dyeing and drying are highly energy-intensive. |
| Steel production | 6–12 | High-temperature furnaces; largely fossil-fuel powered. |
| Cement manufacturing | 4–8 | Large CO₂ process emissions from kilns. |
| Semiconductor fabrication | 50–200 | Extremely energy- and water-intensive cleanrooms. |
| Plastic polymer production | 3–8 | Chemical processing, fossil-fuel feedstocks. |
Conclusion
While RAS is sometimes criticized for high energy use, its demand is modest compared to many industrial sectors—and importantly, it represents environmental accountability. By internalizing water treatment and waste management, RAS shifts ecological burdens into controlled, measurable processes.
As renewable energy adoption increases and RAS system designs continue to improve, land-based aquaculture has the potential to become one of the world’s most sustainable sources of animal protein—both environmentally and economically.
IWH, Oct 2025