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 sturgeon Acipenser fulvescens, fish were netted from two sites: Riviere des Prairies, confluent with the St. Lawrence River near Montreal, and a reference site on the upper reaches of the Ottawa River in the La Verendrye Park. Livers of fish collected from the Riviere des Prairies were difficult to homogenize, and they left behind strands of what appeared to be connective tissue. Suspecting hepatic fibrosis, we decided to evaluate the livers for histopathologic changes. Nineteen adult lake sturgeon (eleven male and eight female) were examined. Following fixation, routine processing, sectioning, and staining with hematoxylin and eosin, microscopic evaluation revealed the following: Sections taken from livers of fish from the Riviere des Prairies site showed excessive fat accumulation and often severe chronic-active cholangiohepatitis. Bile duct proliferation (P < 0.0001), periportal fibrosis (p < 0.0001), inflammation (p < 0.001), and fat accumulation (p < 0.05) were more pronounced in the fish from the Rivitre des Prairies site. Melano-macrophage centres appeared to be both paler and gave the appearance of fewer numbers (p < 0.01). Livers from lake sturgeon taken from the reference site had a more normal appearance. The EROD levels were also significantly induced in these fish (reference 3.39 +/- 0.57; Riviere des Prairies site 8.21 +/- 0.87 pmol/mg protein/min; (p < 0.0005). The EROD levels positively correlated with bile duct proliferation (r(2) = 0.44; p = 0.001) and periportal fibrosis (r(2) = 0.41; p = 0.002). Despite the statistical associations above, we cannot categorically state that contaminants are the sole cause of the lesions seen.