Rainbow trout is farmed in Northern Europe in cages, ponds, flow-through systems and RAS systems using hatchery-produced juveniles. Farming depends on feed containing a relatively high proportion of fishmeal and fish oil. The origin of the raw materials is generally well traceable. In Norway, no genetically modified ingredients are used. In Sweden, their use is not always clear to consumers. RAS systems require more energy but have the lowest environmental impact.
Open farming systems can result in moderate to high nutrient loads in surface waters. Escapes and the spread of diseases remain concerns, particularly in cage farming. Measures have been introduced in Norway and Sweden to reduce escapes and predation. Antibiotics and other chemical treatments may be used, but major disease outbreaks are uncommon. RAS systems limit waste emissions, prevent escapes and reduce the risk of disease transmission. However, CO₂ emissions from RAS are higher because of their energy consumption.
Management is largely effective in Northern Europe. There is no AIP for this aquaculture. In Norway, many farms are certified according to ASC, BAP and GlobalG.A.P. In Sweden, Switzerland and Finland, few or no farms are ASC-certified. Denmark has a strict regulatory framework for aquaculture, and RAS systems are among the most sustainable production methods there.