Potential Effects of Contaminants on Fraser River Sockeye Salmon

The results <strong>of</strong> this analysis indicate that bioaccumulation <strong>of</strong> contaminants in fish tissues hasthe potential to adversely affect the productivity <strong>of</strong> sockeye salmon stocks in the FraserRiver Basin. Siska Traditions Society (2009) collected eggs and muscle from WeaverCreek and Adams River sockeye salmon and from Thompson River chinook salmon.These tissue samples were analysed to determine the concentrations <strong>of</strong> metals andpesticides (Table 5.21 and 5.22). Comparison <strong>of</strong> the measured concentrations <strong>of</strong> thesecontaminants to the selected toxicity reference values indicates that the concentrations <strong>of</strong>selenium and 2,3,7,8-TCDD toxic equivalents in salmon eggs were sufficient to adverselyaffect fish reproduction (Table 5.20).In 2001, Kelly et al. (2007) collected early-run Stuart and Weaver Creek sockeye salmonat up to five locations along the approach to and within the Fraser River. Samples <strong>of</strong>muscle, eggs, testes, and/or liver were obtained at each sampling site for each sockeyesalmon population. The concentrations <strong>of</strong> PCBs, PCDDs, and PCDFs were measured ineach tissue sample collected, with the results expressed as 2,3,7,8-TCDD toxicequivalents. The maximum concentration <strong>of</strong> 2,3,7,8-TCDD in salmon roe from these twostocks was 0.89 pg/g lipid, which is below the toxicity threshold <strong>of</strong> 3.0 pg/g lipid in eggs(Table 5.23). However Debruyn et al. (2004) measured concentrations <strong>of</strong> PCBs, PCDDs,and PCDFs, in conjunction with contaminant magnification factors, to model the levels <strong>of</strong>2,3,7,8-TCDD toxic equivalents in the eggs <strong>of</strong> sockeye salmon migrating various distancesin the Fraser River Basin. The results <strong>of</strong> this study indicated that the eggs <strong>of</strong> AdamsRiver, Chilko River, and Stuart River sockeye salmon could have 3.4 to 6.9 pg/g lipid <strong>of</strong>2,3,7,8-TCDD toxic equivalent by the time these stocks reached their natal streams (Table5.23). These levels exceed the toxicity threshold <strong>of</strong> 3 pg/g for salmon eggs, which isassociated with 30% mortality <strong>of</strong> fish eggs. These latter results suggest that PCBs,PCDDs, and PCDFs could be adversely affecting sockeye salmon reproduction in thestocks that migrate substantial distances to their spawning grounds.5.5 Summary <strong>of</strong> the Evaluation <strong>of</strong> the <strong>Potential</strong> <strong>Effects</strong> <strong>of</strong> <strong>Contaminants</strong> <strong>of</strong>Concern on Fraser River Sockeye SalmonA risk-based approach was used to evaluate the potential effects on sockeye salmonassociated with exposure to aquatic contaminants in the Fraser River Basin. Thisapproach involved:• Refining the list <strong>of</strong> contaminants <strong>of</strong> concern;70