Metal contamination of angler-caught fish from the Mersey Estuary

A survey of angling in the Mersey Estuary was undertaken to determine geographical and seasonal patterns of angling, the dominant species and size range of retained fish, and the fate of the catch. Six core species of fish were sampled from five sites in the Mersey Estuary, Hoylake, on the north Wirral, and a reference site in the Solway Firth. Analysis of muscle tissue was undertaken for mercury, arsenic, lead, copper, zinc, chromium and cadmium. Mean mercury levels for the eel and flounder populations from most Mersey Estuary sites exceeded the limit values of 0.5 and 1.0 mg kg−1 for fishery products, as specified in EC Decision (93/351/EEC). Inner Mersey Estuary sites also showed mean concentrations of lead in eel and flounder in excess of the statutory limit of 2.0 mg kg−1. Arsenic levels were higher than the general UK food limit of 1.0 mg kg−1, but the toxicological significance of this is minimal. All other combinations of species-site-metals returned data consistent with expected ranges and which are of no concern to human health. Whilst the real practical risk to consumers of Mersey Estuary fish may be low, the concentrations of mercury in muscle reinforce the prudence of MAFF advice to abstain from the consumption of long-lived lipid(fat)-rich fish, especially eels, from industrialised estuaries such as the Mersey.