Effects of Neutral Sulfite Semichemical Pulp Mill Effluent in the Mummichog (Fundulus heteroclitus) Adult Fish Reproductive Test

Short-term adult fish reproductive tests using freshwater species have demonstrated negative impacts on egg production in fish exposed to complex pulp and paper mill effluents. In an effort to address the ability of laboratory tests to predict effects on wild fish, mummichog (Fundulus heteroclitus) were exposed in saltwater conditions for 21 days to 3 and 30% final effluent of a neutral sulfite semichemical pulp mill that discharges into an estuarine environment in eastern Canada. Although no effects on gonad size, liver size, or condition factor were found, egg production was significantly increased by 31% and decreased by 30% when fish were exposed to 3 and 30% final effluent, respectively. This study i) is the first to demonstrate a decrease in egg production when fish are exposed to complex effluents under estuarine conditions and ii) provides the first linkage of effects on gonad size in wild fish to egg production from laboratory testing in the same species. In so doing, this study also demonstrates the utility of egg production measurements to further investigate the causes and solutions to the effects of mill effluents in both freshwater and marine wild fish.