Perspectives on Canadian field studies examining the potential of pulp and paper mill effluent to affect fish reproduction.

The results and interpretations of published Canadian field studies on the reproductive status of fish in waters receiving pulp and paper mill effluent discharges were reviewed. Most of the information was obtained from indicator measurements such as gonad size, fecundity, and serum steroid levels in wild fish sampled at reference and effluent-exposed sites. Difficulties in selecting appropriate sampling sites, natural variability, and the ecological relevance of the indicator measurements were identified as major complicating factors for the interpretation of the field data. Consequently, it was not possible to conclude to what extent, if any, widespread effects on fish reproduction are being caused by pulp and paper mill effluents or that specific manufacturing processes are causing such effects. Further research on the normal variability and predictive capability of reproductive indicators, for example, using an integrated approach (i.e., laboratory testing, mesocosm studies, and field work), is recommended.