Recirculating aquaculture is becoming increasingly popular the world over. This is due to the method’s environmentally friendly nature and the opportunity to farm fish under optimal conditions around the year.

Recirculating aquaculture is a fish farming method in which water is circulated by pumping it from fish tanks into cleaning units and back. The method helps to save water, since the new water accounts for only between 1% and 2% of the volume of circulating water. In recirculating aquaculture, the technology used for cleaning the water can also significantly reduce the nutrient load. The phosphorus discharge tends to be around 20 per cent of that of traditional fish farming methods. While the removal of nitrogen is more difficult, the related techniques are under continuous development.

Recirculating aquaculture requires substantial investments in technology, among other things, while maintenance costs are high due to energy consumption and other factors. For this reason, this technology has not yet been competitive for the farming of mass species such as rainbow trout. Until now, recirculating aquaculture in Finland has been used in the farming of more valuable species such as sturgeon, Arctic char, European whitefish and zander.

An experimental research and learning environment is in operation at the Laukaa fish farm of the Natural Resources Institute Finland. This development environment can be used to identify solutions in collaboration with entrepreneurs. It assists in the trialling of technical solutions in fish farming development and examining the biological limits that are important to fish culture. Instruments that monitor water quality on-line may also be used to develop recirculating feeds, thereby modernising production.

Picture on top of the page: Luke’s photo archive

See also