Norway expands fish feed monitoring to track new contaminants

NORWAY – Norway has widened its national fish feed monitoring program to include a new range of contaminants, with the 2024 results showing largely low levels of harmful substances but highlighting some emerging areas of concern. 

The findings, published in the Norwegian Food Safety Authority’s (NFSA) annual report, are critical for ensuring the safety of aquaculture feed in one of the world’s largest salmon-producing nations.

The monitoring program, carried out on behalf of the NFSA by the Norwegian Institute of Marine Research (HI), examined 99 fish feeds and 48 feed materials, including fishmeal, fish oil, plant meals, insect meal, algae oil, krill meal and yeast, intended primarily for Atlantic salmon.

Samples were analysed for heavy metals, pesticides, feed additives, emerging contaminants, microbes, and nutrients.

New focus on emerging contaminants

According to HI researcher Anne-Katrine Lundebye, 2024 marked the first time that the program tested for substances not previously included. “What is new in the 2024 report is that we have included unwanted substances (emerging contaminants) that have not been analysed in this monitoring program before,” she said.

Among these were brominated flame retardants and chlorinated naphthalenes—industrial chemicals known to persist in the environment. Only one such contaminant, tribromoanisole, was detected, a breakdown product of the flame retardant tribromophenol. 

Lundebye noted that these results will feed into broader European research efforts: “The European Food Safety Authority (EFSA) is requesting more data on bromophenols and chlorinated naphthalenes in food and feed. Data from us can be used in their work towards any future risk assessments for such substances.”

Heavy metals, PFAS and pesticides under review

The report also tracked heavy metals such as arsenic, mercury, and cadmium. Levels were below European limits across all samples, though concentrations were higher in starter feed compared to grow-out feed. 

“One explanation may be that starter and smolt feed contain more marine ingredients than the various grow-out feeds do. It is known that the levels of the aforementioned substances are typically higher in marine raw materials than in plant-based raw materials,” Lundebye explained.

For the first time, researchers employed improved methods to detect per- and polyfluoroalkyl substances (PFAS), a group of persistent pollutants.

Perfluorooctane sulfonamide (FOSA) was present in 73% of starter feeds, 54% of smolt feeds, and 27% of grow-out feeds. It was also found in 88% of fishmeal samples. 

Other PFAS, including PFOS and PFOA, appeared in fewer than 20% of samples. By contrast, insect- and algae-based ingredients showed no measurable PFAS.

On pesticides, traces of several substances were detected. The highest levels of cypermethrin and deltamethrin were found in wheat gluten, a plant meal ingredient. 

Chlorpyrifos, an insecticide no longer authorised in the EU, was present in all feed samples but at very low concentrations, likely reflecting environmental residues.

Absence of ethoxyquin and other findings

Unlike in past years, no traces of the antioxidant ethoxyquin, formerly used in fish feed, were detected. Microbial testing showed no Salmonella or Listeria, and no ruminant proteins were found in fishmeal. 

However, two samples of corn gluten meal recorded unusually high levels of the mycotoxin ochratoxin A, underscoring the importance of continued vigilance.

The NFSA emphasised that these monitoring results are vital for developing future safety standards. “These data on contaminants in fish feed and feed ingredients are important for risk assessment authorities and for generating occurrence data, which is required for setting future maximum levels for unregulated contaminants,” the report noted.

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