Norwegian fish farms polluting fjords with waste likened to ‘raw sewage of millions of people’ | Norway

Norwegian fish farms fill fjords and other coastal waters with nutrient pollution equivalent to the raw sewage of tens of millions of people every year, a report says.

Norway is the largest producer of farmed salmon in the world and nutrients in fish feed are excreted directly into coastal waters. An analysis by the Sunstone Institute found that Norwegian aquaculture released 75,000 tonnes of nitrogen, 13,000 tonnes of phosphorus and 360,000 tonnes of organic carbon in 2025.

The nutrients are equivalent to those in the untreated wastewater of 17.2 million people for nitrogen, 20 million people for phosphorus and 30 million people for organic carbon, the report said, raising fears of destructive algae blooms.

“Norway is a small country of only 5.5 million people, and aquaculture pollution in terms of these three nutrients is three to five times higher than the population,” said Alexandra Pires Duro, data scientist at Sunstone and author of the report. “Feces, uneaten food, urine – it all goes into the water. »

Fish on farms are fed nutrient-rich food pellets in open-net cages as they are raised for human consumption. Analysts calculated the mass of nutrient inputs remaining in the water using data from the National Fisheries Directorate and the Veterinary Institute.

The researchers found that food consumption increased by 14.6% over a six-year period, alongside the industry’s expansion, producing nutrient pollution by 2025 equivalent to levels expected in the raw sewage of a country the size of Australia. In a separate analysis, the report’s authors found that seasonal variations made the problem worse, with nutrient load being higher during the summer months, when ecosystems are least able to absorb it.

Fish slime from nutrients can fertilize phytoplankton and lead to destructive algae blooms that deplete oxygen levels. Fjords are particularly vulnerable to such effects because they are semi-enclosed bodies of water, allowing greater accumulation of nutrients. Their oxygen levels are already decreasing due to global warming.

In the Sognefjord, the country’s longest fjord, increased nutrient inputs – and not just from fish farms – were blamed for about two-thirds of the oxygen depletion, according to a study last year, while warmer water was blamed for the other third.

Oxygen levels in deep waters have also decreased in Norway’s second longest fjord, the Hardangerfjord, according to the governor of Vestland.

In March, authorities rejected nine applications for fish farms in the fjord due to the increased emissions they would cause. Tom Pedersen, an environmental advisor to the region and an expert on the Sunstone report, said the numbers in his analysis were not surprising and were even “on the conservative side.”

“The main concern we’ve had over the last few years is that all of this algae and plankton and everything else is dying, sinking to the bottom of the ground and decomposing – and that process uses oxygen,” he said. “The end result is that the oxygen level in the fjord is decreasing, and has declined further.”

The Norwegian Ministry of Fisheries referred a request for comment to the Directorate of Fisheries, which declined to comment.

Krister Hoaas, head of public affairs at the Norwegian Seafood Federation, the main industry association, said the volume of emissions reflected the amount of food produced in Norway and the degree of self-sufficiency the country would have in an emergency. He said the industry was constantly working to reduce its environmental footprint as much as possible.

“It is important to distinguish between current operations and issues related to future growth,” he added. “The Marine Research Institute is clear that a significant increase in production in some fjord systems could increase the risk of eutrophication locally, but that current production remains largely within nature’s carrying capacity. This provides a basis for strict, site-specific management, but does not prove that current operations are destroying the fjords.”