The European eel Anguilla anguilla (L.) is a widespread, panmictic and catadromous fish, widely distributed over Europe, with an important economic value for fisheries. The population is waning, as shown through recruitment monitoring in European rivers. The state of the stock is now considered below safe biological limits and a recent European regulation urges for stock protection measures. Although many potential causes have been suggested, the reasons for this dramatic decline remain unknownAs the eel is a long-lived, carnivorous, benthic and lipid-rich species, it is particularly prone to the accumulation of noxious chemical compounds, especially lipophilic contaminants like polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and brominated flame retardants (BFRs). At the Research Institute for Nature and Forest, we set up a monitoring network (Eel Pollution Monitoring Network, EPMN) and measured contaminants in the eel over Flanders during a 14-year research programme. Between 1994 and 2007 more than 3000 eels from 376 locations were analysed for PCBs, OCPs, heavy metals and some other compounds. We demonstrated that eels in their yellow stage are very suitable chemical bioindicators; contaminant profiles in those eels are fingerprints of the contamination pressure on the site where they grow up. Monitoring of contaminants in Flanders is based on measuring chemicals in water and sediments, but many analytical results of lipophilic compounds like PCBs and OCPs such as DDT, drins or hexachlorobenzene, fall under the detection limit, whereas in eel, those compounds are detectable in nearly all cases. We therefore strongly recommend a critical assessment of the monitoring strategy of chemical substances in our aquatic environment, both at a Flemish and an international scale, within the European Water Framework Directive. Our results generated a status report and distribution maps of eel pollution for some 30 substances. Most substances are present all over Flanders, but there is considerable ...