Spatial and interspecific patterns in persistent contaminant loads in bighead and silver carp from the Illinois River.

We measured concentrations of selected organohalogens, fluorinated compounds and mercury in whole, ground silver (Hypophthalmichthys molitrix) and bighead (H. nobilis) carp from the Illinois River, Illinois, in 2010 and 2011 to characterize spatial and interspecific patterns of contaminant burdens. Silver carp, which had greater lipid content, tended to have greater concentrations of lipophilic compounds. Concentrations of organohalogens were generally greater in carp from the upper reaches of the river. The halogenated compounds were associated with length and lipid content in silver carp. Bighead carp had greater mercury concentrations than did silver carp; total mercury concentrations were negatively associated with lipid content of bighead carp. Perfluorinated compounds, comprised predominantly of perfluorooctane sulfonic acid, did not vary by species or river reach. Chlordanes and polychlorinated biphenyls were of potential concern with regard to the use of these carp as animal feed additives. Our results indicated that, even though they occupy a lower trophic level than many similarly-sized fish, these carp may accumulate measureable concentrations of organic contaminants.