Low levels of mercury in Norwegian cod
Fillets from cod taken in Norwegian harbours and fjords contain low levels of mercury, according to a new report
“Mercury in cod fillet from the harbors and fjords we have examined is in general not a problem as far as food safety is concerned,” said NIFES scientist Bente M. Nilsen.
NIFES performed the survey, which was commissioned by the Norwegian Food Safety Authority and the monitoring program for polluted harbors and fjords. The results show low concentrations of mercury in fish from all the harbors studied, and significantly lower levels than the EU and Norway's upper permitted limit for mercury (0.5 mg/kg wet weight).
Fillets from 600 cod caught in 15 Norwegian fjords and harbors were analyzed.
Highest levels in Kragerø
Cod from Honningsvåg and Hammerfest contained the lowest levels. In these two harbors the average value for mercury in the fillet lay at the same level as samples from the Barents Sea.
The highest average value, 0.22 mg/kg wet weight, was registered in fish from the area around Kragerø. This was the only port where the average value was higher than 0.2 mg per kg. This is the limit that the Norwegian Food Safety Authority has used when it has issued advisories that pregnant and breast feeding women should avoid eating locally caught cod.
In five ports (Kragerø, Farsund, Stavanger, Karmsundet and Narvik) one or more individual fish with mercury concentrations above the limit were found. These made up from one to five percent of all the fish analysed from each of the areas.
The mercury content increased with the age and size of the fish in several harbours. But no such statistical relationship was found in cod from Sandefjord, Tvedestrand, Lillesand or Svolvær.
A total of nine out of 600 fish examined (1.5 percent) had mercury concentrations at or above the limit.
The survey of mercury in cod fillet is a follow-up of a 2009 report on undesirable substances in wild fish.
This showed very high levels of dioxin and dioxin-like PCBs in cod liver from most harbours, with the exception of Honningsvåg. On the basis of this report, the Food Safety Authority issued an advisory not to eat liver from fish caught close to the coast.
Dioxin and dioxin-like PCBs are environmental contaminants that concentrate in the liver. Because the concentrations were so high in the 2009 survey, it was decided to examine fillets from fish with the highest levels in liver. The result showed that levels of dioxin and dioxin-like PCBs in cod fillets were low. Only one fish displayed levels just above the limit.
“What we have done now is to analyse the same 600 fishes, which have been kept frozen, for mercury. We know that mercury levels can be high in fillets of cod and other lean fish in polluted areas. But our survey shows that this is not the case for cod in the areas that we sampled,” says Bente Nilsen.
The Institute of Marine Research was responsible for collecting the fish samples.