Concentrations of mercury, arsenic, cadmium and lead in Greenland halibut (Reinhardtius hippoglossoides) caught off the coast of northern Norway

In January 2006 it was reported from Russia that Greenland halibut (Reinhardtius hippoglossoides) caught in the Barents Sea had shown mercury levels exceeding the European Union's upper limit of 0.5 mg/kg wet weight (ww) for this species. These findings were confirmed in a small study from the same area. To gain more knowledge, a larger study was initiated to investigate the levels of mercury in Greenland halibut caught off the coast of northern Norway. A total of 320 Greenland halibut were caught in this area in May 2006. Individual fish were filleted and analysed for mercury, arsenic, cadmium and lead. Round weight of the fish varied between 1.1 and 8.1 kg. Fish age varied between 12 and 29 years. The highest mercury concentration measured in muscle tissue was 1.1 mg/kg ww. The highest concentrations were found in female fish. Mercury concentration was positively correlated with fish size and negatively correlated with fat content. Fish captured in the easternmost part of the investigated area had significantly lower mercury concentrations than those caught further west. Fish captured at one of the positions had particularly high average mercury concentrations, 0.52 mg/kg ww, possibly due to a combination of large size, low fat content and different prey availability. The concentrations of arsenic, cadmium and lead in the fillet samples of Greenland halibut ranged from 1.5 to 32 mg/kg ww, <0.001 to 0.02 mg/kg ww and <0.01 to 0.05 mg/kg ww, respectively. Concentrations of arsenic and mercury were positively correlated when all data were included.