Proliferative and neoplastic conditions of flounder (Platichthys flesus) in the northern Baltic Sea in relation to DNA-adducts

A disease survey off the Finnish sea coast of the Baltic Sea included 6644 specimens of flounder (Platichthys flesus). The aim of the survey was to explore to what extent the quality of the coastal environment in the area is reflected in fish health parameters. As degenerative and proliferative conditions of fish liver have increasingly been recognized to be most closely correlated with chemical contaminants special attention was given to this organ. Some neoplastic conditions were recorded in other organs/tissues in the flounders and are reported too. On an average 3.0% of all flounders examined (>20 cm) were affected by preneoplastic/neoplastic liver lesions. The prevalence is significantly increasing with increasing size of fish. Of specimens >30 cm 10.1% were affected and, at one site the disease prevalence in female flounder >30 cm was 31.5%, which must be considered stikingly high. The site not immediately influenced by human activities but in closest contact with the main Baltic Sea, had the highest lesion prevalences. The levels of hydrophobic DNA-adducts in the liver of flounder in the area are low which indicates that, for example, polycyclic aromatic hydrocarbon compounds are not responsible for the high prevalences of proliferative lesions in flounder in this area.