ASSIMILATION EFFICIENCY OF DIETARY METHYLMERCURY BY NORTHERN PIKE (ESOX-LUCIUS)

Northern pike (Esox lucius) retained an average of 19% (range 6-31%) of the methylmercury which they ingested during consumption of young-of-the-year carp (Cyprinus carpio) collected from a pond; carp accumulated methylmercury naturally while in the pond. The total amount of mercury in pike increased with time (up to 42 d) but concentration in the tissue decreased due to growth dilution; duration of ingestion did not influence efficiency of methylmercury assimilation. This value (19%) is considerably lower than most efficiencies reported in the literature, demonstrating that methylmercury in this forage fish is less readily available to a predator fish than previous studies implied.