Nofima study finds warmer freshwater rearing temperatures boost salmon growth at sea.
A new study by the Norwegian Institute of Food, Fisheries and Aquaculture Research (Nofima) has found that Atlantic salmon reared in warmer freshwater conditions continued to outperform cooler-water groups after transfer to sea — contrary to expectations.
The research, conducted at Nofima’s aquaculture station in Sunndalsøra and later at its seawater facility in Gildeskål, tracked salmon reared at 8, 12, and 14 degrees Celsius from 10 grams to harvest size. The fish raised at higher temperatures grew faster both before and after seawater transfer, reaching an average of 140 grams at transfer compared to 70 grams in the coldest group.
“All groups tolerated seawater well, but those reared at warmer temperatures maintained their growth advantage after transfer,” said project scientist Anja Striberny. “We didn’t expect that difference to persist.”
The study, funded by the Norwegian Seafood Research Fund (FHF), also noted mild adverse trends, including smaller heart size and a tendency toward cataracts in the warmest group, particularly among fish reared in recirculating aquaculture systems.
FHF’s Head of Research, Sven Martin Jørgensen, said the results should be viewed in the context of other ongoing projects under the organisation’s “Robust Fish” programme. “When several of these projects have delivered their recommendations, we can compile the findings to identify which early production conditions yield the best-performing farmed salmon,” he said.
Striberny added that while temperatures up to 14 degrees appeared safe — and potentially advantageous — other variables such as stocking density and water quality were controlled and could alter outcomes in commercial settings.
The research was carried out under the Temp-Intens project in collaboration with UiT, the University of Bergen, NTNU, Mowi, Grieg Seafood, and Cermaq.
