CORRELATIONS BETWEEN PATHOLOGICAL-CHANGES AND CHEMICAL CONTAMINATION IN AMERICAN EELS, ANGUILLA-ROSTRATA, FROM THE ST-LAWRENCE RIVER

American eel (Anguilla rostrata) from the St. Lawrence River are heavi ly contaminated with chemicals that mag. be associated with increased incidence of diseases and reproductive impairment. The relationship be tween tissue mirex concentration and body mass was used to separate ee ls into two groups: the proportion of eels migrating from contaminated areas (Lake Ontario and upper St. Lawrence River) increased as the mi gration season progressed. Vertebral malformations and basophilic foci in the liver (preneoplastic lesions) were more frequent at the end of the migratory season, when the eels were more heavily contaminated wi th organochlorine compounds. in contrast, mesenteric nematodes were mo re common in the first week of the season, when eels were less contami nated. Diameters and percentages of different stages of oocytes, and d ensity and surface area of pigmented macrophage aggregates in the sple en, did not vary among weeks. While basophilic aci are specific biomar kers of exposure to environmental contaminants, vertebral malformation s may be caused by a variety of other anthropogenic or natural factors . Further studies are needed to confirm the observed associations betw een chemical contamination and pathological changes.