Nitrogen and phosphorus discharged into fjords match the raw discharge of millions of people, according to a new study

Fish farms in Norway release three times more waste into fjords than the country's entire population produces, new research has suggested.

The findings come from the Sunstone Institute, an Oslo-based research group, which calculated the volume of fish excrement and uneaten feed discharged directly into coastal waters by nearly a thousand fjord-based farms in Norway.

Last year, "the nitrogen and phosphorus in this waste were equivalent to the raw sewage from 17.2 million and 20 million people, respectively," the report said. "Triple the toilet waste from an entire country," it added. Norway's population is about 5.5 million.

The discharge has significant environmental consequences, the report argues. Excess nitrogen and phosphorus trigger algal blooms which, as they decompose, deplete oxygen and create "dead zones" where marine life struggles to survive. Uneaten feed drifting from cages also attracts wild fish, exposing them to elevated nutrient levels and degraded conditions.

The findings stand in contrast to Norway's reputation as a global environmental leader. In the 2024 Environmental Performance Index (EPI), compiled by Yale and Columbia universities, the country ranked 7th out of 180 nations and placed 2nd globally for environmental health.

Norwegian authorities have not yet commented on the findings. Industry representatives have pushed back, with the Norwegian Seafood Federation telling the Guardian that current production remains "well within nature's carrying capacity" and that there is no documented proof that operations are damaging fjords.

The sector is a major pillar of Norway's economy. With the second-longest coastline in the world, the country is the largest producer of farmed salmon, accounting for more than half of global output. It supplies markets across Europe, the US and Asia, exporting 106,000 tonnes worth over $1.1 billion in March alone, according to the Norwegian Seafood Council.

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The industry is dominated by a handful of large Norwegian-based companies, including Mowi, the world's largest salmon farmer, Lery Seafood Group, and SalMar. Profits are concentrated among these major players. Mowi's largest shareholder, shipping magnate John Fredriksen, ranks 118th on Forbes' 2026 global billionaires list with a net worth of $21.2 billion.