Status 2008 – Mercury analyses of seafood from the area around U864 at Fedje
Published:November 10, 2008
Source :NIFES
A new investigation has been carried out analysing mercury in seafood caught from the area around the submarine U864 outside Fedje, Norway. Results show somewhat higher levels of mercury in tusk compared to analyses previous years. The levels of mercury in crab, cod, and ling in the most recent analyses were similar to those found during the period from 2004 to 2007.
10.11.08
The German submarine U864 was torpedoed and sank west of Fedje in 1945. The submarine may have had a cargo of 60-70 tons of mercury when it sank. The wreck lies at a depth of 150 meters and there is a concern that mercury from the cargo, probably spread during the explosion, may contaminate fish in this area. The National Institute of Nutrition and Seafood Research (NIFES) has determined the mercury levels of several species of fish and crab at and around the wreck annually from 2004-2008 in order to assess seafood safety and to monitor year-to-year changes of mercury.
- The new data shows that the mercury levels of tusk captured near U864 in 2008 are somewhat higher than previous years, but we can’t find that the levels are directly linked to the wreck, says senior scientist Amund Måge at NIFES.
- It is difficult to determine whether the mercury levels in fish caught near the wreck is elevated compared to background levels for this area, since there are hardly any data of the background levels of mercury from this region. The variation of mercury in seafood from the area over time may be random and cannot be taken as a proof of increased mercury levels nearby, although this may be the reason.
The Norwegian Food Safety Authority has previously given dietary advice concerning seafood from the region, where pregnant and breastfeeding women are recommended to avoid eating seafood from the area around the submarine. ’The Norwegian Food Safety Authority upholds dietary advice’ (from January 2008 only in Norwegian). Apart from this, the new analyses does not change the food safety situation in the area, says Måge. Higher levels of mercury in tusk for 2008 compared to previous years:
Tusk: Mercury levels in fillets of tusks caught in 2008 at the site of the wreck of U864, as well as two nautical miles north and four nautical miles south of the wreck, varied from 0,14 to 0,73 mg/kg wet weight. Twelve of the 75 tusks analysed showed a mercury concentration over EU’s maximumlimit of 0,5 mg/kg wet weight. Although more of the analysed fish had mercury concentrations over the limit than in previous years, the mercury levels are not considered to be especially high compared to levels found in tusk from presumably uncontaminated areas in Sunnmøre and the Norwegian Sea in 2007. Tusk caught at the wreck site had a lower mercury concentration compared to tusk caught further south and north, suggesting that there is no connection between contamination from the wreck and levels of mercury in fish from the area.
Mercury levels of crab, cod and ling in 2008 are similar to previous years:
Crab: Data from 2008 shows that mercury levels in crab from the area were similar to results from previous years, and were higher in brown meat compared to white meat. Brown meat from crabs caught at the wreck had elevated levels of mercury compared to crabs caught two nautical miles north of the wreck and four nautical miles south of the wreck. This suggests that crabs from the area are under the influence of mercury from the wreck. Two out of 23 samples of brown meat from crab taken by the wreck had a concentration of mercury over EU’s maximum limit for crustaceans of 0,5 mg/kg wet weight. However, this maximum limit does not include brown meat from crab.
Cod: Determination of mercury in cod during the period from 2004 to 2008 shows higher levels of mercury compared to what are considered background levels of fish and crabs caught in the open seas and presumably uncontaminated areas (www.nifes.no/seafooddata). However, very few cod from the area around U864 have been analysed. In 2008, only one cod was caught and this fish had a mercury content below EU’s maximum limit of 0,5 mg/kg wet weight.
Ling: Three lings were caught in 2008. Analysis showed that their mercury concentrations were below EU’s upper limit of 0,5 mg/kg wet weight, and showed similar levels compared to previous years.
Photo of Crab caught near U864 in 2008 (Photo: NIFES)
Mercury in the marine environment
Mercury exists in several chemical forms, of which methyl mercury is the most toxic one and the form that accumulates in the food chain. In sediments, mercury is mainly found as inorganic mercury (>99%). Bacteria convert inorganic mercury to the organic form (mainly methyl mercury), and it is this form that enters the food chain. Methyl mercury is the most common form of mercury in fish. EU’s upper limit for mercury is based on the total amount of mercury in a sample, and the analysis of seafood from the area outside Fedje is therefore also based on total mercury.
Traffic and fishing ban
Based on analyses from 2004 to 2007 and an assessment of the actual wreck, a traffic and fishing ban has been imposed for a radius of 500 metres around the wreck, and the Norwegian Food Safety Authority has given a dietary recommendation advising pregnant and breastfeeding women to avoid eating fish caught in the vicinity of the wreck. ’The Norwegian Food Safety Authority upholds dietary advice’ (from January 2008 only in Norwegian).
NIFES recommends continued monitoring
Since some of the mercury analyses of seafood from the area around U864 have shown a concentration of mercury above EU’s upper limit, and because the diffusion pattern of mercury may change, it is important to continue monitoring the mercury content of fish in this area outside of Fedje.
NIFES is responsible for giving research based advice to the government and food authorities concerning health and safety aspects of seafood both from wild catch and farmed fish, and the institute has spent the last 15 years carrying out research on environmental toxins in seafood.
Summary of analyzed species in the period 2004 to 2008:
