50,000 rainbow trout swim in a single sea pen off Korsnäs
Wednesday 10th June 2026 on 17:45 in
Finland
Nordic Trout has invested over €5 million in offshore rainbow trout farming in Korsnäs, with plans to expand its sea pens from four to eight by next summer, Yle reports.
The company received environmental approval for the operation in December 2023 without any objections, marking the first such permit for offshore fish farming in Finland. Authorities are increasingly encouraging a shift from coastal to open-sea aquaculture, where conditions are often better for the fish.
Each circular sea pen, anchored about 10 km off the coast, has a circumference of 120 metres and a net depth of 15 metres. One pen currently holds 50,000 rainbow trout, with five pens totalling roughly 750,000 kg of fish this year. Stocking density is carefully monitored to prevent stress, according to Nordic Trout’s business director Jussi Kosomaa.
The pens are covered with nets to prevent fish from jumping out in storms and to deter predatory birds. Daily feedings involve firing pellets through the nets with a specialized cannon, triggering fierce competition among the fish. The feed is precisely measured to ensure even distribution.
Nordic Trout, part of the Nordic Fish Group, operates across mainland Finland, Åland, and Sweden, with processing plants in Kustavi and Åland. The company controls the entire production chain, from broodstock and egg incubation to offshore growth, where the trout reach about 3 kg in three years before harvest.
Open-sea farming has significantly reduced environmental impact compared to earlier decades, now contributing roughly 1% of the Baltic Sea’s total nutrient load, according to Luonnonvarakeskus (Luke) researcher Pia Lindberg. Improved feed and technology, along with better dispersion of nutrients in deep waters, have made offshore aquaculture one of the most ecological options available.
The company chose Korsnäs due to smooth permitting and expansion potential, with plans for three separate offshore farms within a 10 km radius. A proposed new processing plant in Korsnäs could employ about 20 seasonal workers.