EVALUATION OF LIVER HISTOPATHOLOGY AND EROD ACTIVITY IN ST-LAWRENCE LAKE STURGEON (ACIPENSER-FULVESCENS) IN COMPARISON WITH A REFERENCE POPULATION

In an attempt to evaluate the effects of contaminants on the lake stur geon Acipenser fulvescens, fish were netted from two sites: Riviere de s Prairies, confluent with the St. Lawrence River near Montreal, and a reference site on the upper reaches of the Ottawa River in the La Ver endrye Park. Livers of fish collected from the Riviere des Prairies we re difficult to homogenize, and they left behind strands of what appea red to be connective tissue. Suspecting hepatic fibrosis, we decided t o evaluate the livers for histopathologic changes. Nineteen adult lake sturgeon (eleven male and eight female) were examined. Following fixa tion, routine processing, sectioning, and staining with hematoxylin an d eosin, microscopic evaluation revealed the following: Sections taken from livers of fish from the Riviere des Prairies site showed excessi ve fat accumulation and often severe chronic-active cholangiohepatitis . Bile duct proliferation (P < 0.0001), periportal fibrosis (p < 0.000 1), inflammation (p < 0.001), and fat accumulation (p < 0.05) were mor e pronounced in the fish from the Rivitre des Prairies site. Melano-ma crophage centres appeared to be both paler and gave the appearance of fewer numbers (p < 0.01). Livers from lake sturgeon taken from the ref erence site had a more normal appearance. The EROD levels were also si gnificantly induced in these fish (reference 3.39 +/- 0.57; Riviere de s Prairies site 8.21 +/- 0.87 pmol/mg protein/min; (p < 0.0005). The E ROD levels positively correlated with bile duct proliferation (r(2) = 0.44; p = 0.001) and periportal fibrosis (r(2) = 0.41; p = 0.002). Des pite the statistical associations above, we cannot categorically state that contaminants are the sole cause of the lesions seen.