Potential Effects of Contaminants on Fraser River Sockeye Salmon

Interest and in the South Thompson River Area <strong>of</strong> Interest. However, it is unlikely thatcontaminated sediments represents a significant factor in the decline <strong>of</strong> sockeye salmonover the past 20 years because interactions between sockeye salmon and contaminatedsediments are likely to be minimal under most circumstances and the identifiedcontaminants <strong>of</strong> concern are not highly bioaccumulative. More information is needed t<strong>of</strong>ully evaluate the potential effects <strong>of</strong> contaminated sediments on Fraser River sockeyesalmon, particularly for highly bioaccumulative substances and contaminants <strong>of</strong> emergingconcern.Accumulation <strong>of</strong> contaminants in fish tissues represents a potentially important factorinfluencing the status <strong>of</strong> sockeye salmon populations in the Fraser River Basin. Theresults <strong>of</strong> this evaluation showed that selenium and 2,3,7,8-TCDD toxic equivalentsoccurred in salmon eggs at concentrations sufficient to adversely affect sockeye salmonreproduction. In addition, 2,3,7,8-TCDD toxic equivalents are predicted to reach levelsassociated with egg mortality in up-river sockeye salmon stocks. While the magnitude andextent <strong>of</strong> such effects could not be determined with the available data, bioaccumulationmediatedeffects could be important contributing factors to the decline <strong>of</strong> sockeye salmonin the Fraser River Basin over the past two decades. In particular, the interactive effects<strong>of</strong> elevated water temperatures, infection by various disease agents, and bioaccumulation<strong>of</strong> toxic substances warrants further evaluation (See Chapter 6 for further information).72