Salmon Farming Pollution Threatens Norway’s Fjords

According to a Guardian report citing an analysis by the Sunstone Institute, salmon farming is causing significant nutrient pollution in Norway’s fjords and coastal waters. Norway, the world’s largest producer of farmed salmon, releases nutrients directly into the sea as fish are fed in open-net cages.

The Sunstone Institute estimates that 75,000 tonnes of nitrogen, 13,000 tonnes of phosphorus and 360,000 tonnes of organic carbon will be released in this way in 2025.

The figures are comparable to the untreated sewage generated by tens of millions of people. According to the analysis, the nitrogen load alone is equivalent to sewage from 17.2 million people, while the phosphorus and organic carbon loads correspond to 20 million and 30 million people respectively. Experts warn that such nutrient pollution can fuel algal blooms and subsequent oxygen depletion.

The amount of feed used by the industry has risen by 14.6% in six years, alongside the expansion of salmon farming. The problem is particularly acute in summer, when ecosystems are less able to absorb nutrients. Fjords are sensitive to such changes because they are semi-enclosed bodies of water.

In the Sognefjord, increased nutrient inflows, not only from fish farms, were found to account for about two-thirds of the decline in oxygen levels. Oxygen levels have also fallen in the Hardangerfjord. In March, local authorities in Vestland halted applications for new or expanded aquaculture sites in the fjord, while the industry argues that current production remains within nature’s carrying capacity.

(guardian, bak)