Seasonal variation in the levels of organohalogen compounds in herring (Clupea harengus) from the Norwegian Sea

► Organohalogen compounds have been analysed in 800 herring from the Norwegian Sea. ► Concentrations of PCDD/Fs and dl-PCBs, PCB7 and PBDEs in NSS herring are low. ► Herring show strong seasonal variations in levels of organohalogen compounds. ► Concentrations of organohalogen compounds in herring decrease during spawning.