Eels: Contaminant cocktails pinpointing environmental contamination

There is growing concern that insufficient somatic and health conditions of silver European eels (Anguilla anguilla) emigrating from European waters to oceanic spawning areas might be a key causative factor in the decline of the stock. One factor that could contribute to deterioration in the status of eels is high contaminant accumulation in their body. Contaminants may affect lipid metabolism and result in lower energy stores. A high body burden of contaminants and low energy stores might be responsible for failure of migration and/or impairment of successful reproduction. During a 12-year study on a relatively small area within the river basins of IJzer, Scheldt, and Meuse (ca. 13 500 km²), 2613 eels were sampled covering a dense monitoring network of 357 stations. Eels were analysed for ca. 100 chemicals. These included PCBs, organochlorine pesticides, heavy metals, brominated flame retardants, volatile organic pollutants (VOCs), endocrine disruptors, dioxins, perfluorooctane sulphonic acids (PFOSs), metallothioneins, and polycyclic aromatic compounds. This series represents only a very small fraction (30 000 chemicals currently marketed and used in Europe. The biomonitoring value of eels as a tool for monitoring environmental contamination is illustrated. Two major conclusions were drawn: (i) the eel is a highly suitable biomonitor for environmental contaminants, for both local and international purposes, e.g. to evaluate the chemical status for the Water Framework Directive, and (ii) dependent on the degree of pollution in their habitat, the levels of certain contaminants reported in yellow eels can be high, and might affect their potential for reproduction.