Trends in hepatic tumours and hydropic vacuolation, fin erosion, organic chemicals and stable isotope ratios in winter flounder from Massachusetts, USA

Liver lesions including neoplasia and hydropic vacuolation have been described in winter flounder (Pleuronectes americanus) from sites in Boston Harbor, and were highly prevalent near the Deer Island sewage outfall. A marked decline in prevalence of neoplasia has been seen over the period 1987 to 1993 in fish from near the Deer Island outfall. This decline in disease in Deer Island fish correlated with and probably resulted from reported reduced chemical input over that time. Stable isotope ratios suggest that Deer Island winter flounder, in contrast to fish from elsewhere, fed significantly on sewage sludge-derived organic matter prior to 1992 and that their along-shore movement is slight. Between 1991 and 1993 hydropic vacuolation remained much more prevalent in flounder taken near Deer Island and another sewage outfall, than at sites distant (≤45 miles) from the outfalls. Hydropic vacuolation prevalence correlated closely with content of chlorinated hydrocarbon residues in the liver, and in particular with DDT/DDD/DDE. This suggests that between 1991 and 1993 there was a persistent chemical-associated difference in fish from the planned and current outfall sites, and that monitoring of winter flounder will provide necessary assessment of altered chemical carcinogenesis risk during and after the switch to the offshore outfall planned for 1998