A MAJOR study in Norway has found that wild salmon contains more contaminants than farmed salmon, reversing a popular held view that it was the other way around. But neither are harmful to health, it is being stressed.
NIFES, the Norwegian Institute of Nutrition and Seafood Research, carried out the extensive study, led by senior researcher at NIFES, Professor Anne-Katrine Lundebye. The team studied differences in contaminants and nutrients between the two types of salmon.
These include dioxins, PCBs, brominated flame retardants and most pesticides, as well as differences in what the fish were eating.
Lundebye told forskning.no that 100 wild salmon caught off northern Norway and a similar number of farmed salmon were used in the experiment.
The results were quite clear and show that farmed salmon had lower levels of organic pollutants than their wild counterparts.
It was also pointed out that fish farms control what their salmon can eat, but nature decides what wild fish consume.
Lundebye believes the development of fish feed is one of the reasons for the relatively low level of organic contaminants in farmed salmon. She stressed that both types of salmon provided healthy omega-3 oils and were quite safe to eat.
Salmon from the Norwegian Sea were used in the trial because it is the main nursery area for this species of fish.
The last major study carried out in this field was in the United States more than 12 years ago and it came to the opposite conclusion to this latest NIFES research, sparking off a major debate at the time.
Lundebye pointed out that the 2004 US study involved comparing wild Pacific salmon with farmed Atlantic salmon, two different species with two different types of fat cell content which do not bear comparison.
The study reference is: Lundebye, AK: ‘Lower levels of persistent organic pollutants, metals and the marine omega-3 fatty acid DHA in farmed compared to wild Atlantic salmon (Salmo salar)» Environmental Research (2017).