Investigation of impacts on white sucker (Catostomus commersoni) populations from Jackfish Bay to over 20 years of changes in pulp mill effluent discharges

摘要

The impacts of pulp mills effluents on fish and fish habitat have been studied at Jackfish Bay, Lake Superior, Ontario, Canada since the late 1980's. Jackfish Bay has received the effluent from a large bleached kraft pulp mill (BKM) in Terrace Bay, ON since 1948. The site is isolated from other sources of contamination, industrial or municipal effluents. Ongoing studies conducted since 1988, showed that white suckers (Catostomus commersoni) had a number of reproductive alterations, including delayed maturity, decreased gonadal size, decreased expression of secondary sexual characteristics, and depressed levels of circulating steroids. Reductions in gonad size and steroid levels persisted until the pulp mill closed its hardwood line in the late fall of 2005, and ceased all effluent discharge from its softwood line from February 2006 to September 2006. Fish were collected in the spring and fall of 2006 during shutdown, and then again 8 months after the mill reopened. The mill subsequently closed for ＞16 months, and fish were sampled after the mill reopened; sampling continued in 2011. This paper will discuss the pace of recovery after closures, and continuing concerns about the impacts of pulp mill effluents on fish reproduction.