Mercury, cadmium and lead in eels and roach: the effects of size, season and locality on metal concentrations in flesh and liver.

Mercury, cadmium and lead were measured in the liver and flesh of 885 eels and 338 roach collected from four sites on the Rivers Brett and Chelmer, eastern England, over the period November 1985 to November 1987. Concentrations of metals in liver and flesh of both species were highly correlated at all sites. Generally, mercury in flesh and liver was correlated with fish length in both species. There were fewer significant relationships between length and the concentrations of cadmium and lead. Site differences in mean concentrations were recorded. Seasonal variations in metal concentrations were largely restricted to eels from the more polluted Site 4. The significance of the concentrations of metals to the status of the fishery is discussed.