Measurement of contaminants in food for Marine Strategy Framework Directive descriptor 9 | Scottish Marine and Freshwater Science Vol 6 No 11

A sampling programme targeting appropriate fish species was recently designed for Descriptor 9. This design was based around existing fish stock assessment research vessel surveys, with fish sampled from each trawling location with a probability proportional to the landings by the Scottish fishing fleet. Haddock, monk and herring were selected based on their importance to the human diet (based on fish landings) and to represent different groups of fish (e.g. high trophic level, high fat content). Using this sampling design, samples were collected in 2013 and 2014 and the muscle tissue analysed for polychlorinated biphenyls (PCBs) and trace metals.

Descriptor 9 (Contaminants in fish and other seafood for human consumption do not exceed levels established by Community legislation or other relevant standards) is one of eleven Marine Strategy Framework Directive (MSFD) qualitative Descriptors to be used in determining whether Good Environmental Status (GES) has been achieved for European regional seas (Directive EC/2008/56). For monitoring of compliance with GES for Descriptor 9, contaminant concentrations in fish and seafood should be compared against the EC regulatory levels. PCBs were mainly below detection limits in monkfish and haddock, but above detection limits in herring where concentrations for the ICES6 CBs ranged from < LoD (in one sample only) to 17.5 µg kg-1 wet weight. For metals, Cd and Pb were mainly below detection limits, whereas Hg was detected in all samples. Concentrations of Hg were higher in monkfish than in haddock and herring. Although monkfish has a low lipid content, it is at the highest trophic level of the three species. Cd, Hg, Pb and the ICES6 PCB concentrations were below the regulatory levels in all samples. The 95th percentile of the distributions of the trace metal and ICES6 PCBs concentrations were estimated for each species and area and compared against the regulatory limits. All were significantly below the regulatory levels, except for mercury in monkfish from the West coast.