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Potential Effects of Contaminants on Fraser River Sockeye Salmon

Potential Effects of Contaminants on Fraser River Sockeye Salmon

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Chapter 7 Uncertainty and Data Gap Analysis7.0 Introducti<strong>on</strong>There are a number <str<strong>on</strong>g>of</str<strong>on</strong>g> sources <str<strong>on</strong>g>of</str<strong>on</strong>g> uncertainty in assessments <str<strong>on</strong>g>of</str<strong>on</strong>g> risk to sockeye salm<strong>on</strong>associated with exposure to c<strong>on</strong>taminants in the <strong>Fraser</strong> <strong>River</strong> Basin, includinguncertainties in the c<strong>on</strong>ceptual model (i.e., pathway analysis), uncertainties in the effectsassessment, and uncertainties in the exposure assessment. As each <str<strong>on</strong>g>of</str<strong>on</strong>g> these sources <str<strong>on</strong>g>of</str<strong>on</strong>g>uncertainty can influence the estimati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> risk, it is important to describe and, whenpossible, quantify the magnitude and directi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> such uncertainties. The purpose <str<strong>on</strong>g>of</str<strong>on</strong>g> thissecti<strong>on</strong> is to evaluate the uncertainty in a manner that facilitates the attributi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> the level<str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>fidence that can be placed in the assessments c<strong>on</strong>ducted using the various lines <str<strong>on</strong>g>of</str<strong>on</strong>g>evidence. Accordingly, the uncertainties associated with the assessment <str<strong>on</strong>g>of</str<strong>on</strong>g> risks to <strong>Fraser</strong><strong>River</strong> sockeye salm<strong>on</strong> are described in the following secti<strong>on</strong>s. Key data gaps are alsoidentified.7.1 Uncertainties Associated with the C<strong>on</strong>ceptual ModelThe c<strong>on</strong>ceptual model (i.e., including the pathways analysis) is intended to define thelinkages between stressors, potential exposure, and predicted effects <strong>on</strong> ecologicalreceptors. As such, the c<strong>on</strong>ceptual model provides the scientific basis for selectingassessment and measurement endpoints to support the risk assessment process. <str<strong>on</strong>g>Potential</str<strong>on</strong>g>uncertainties arise from lack <str<strong>on</strong>g>of</str<strong>on</strong>g> knowledge regarding ecosystem functi<strong>on</strong>s; failure toadequately address spatial and temporal variability in the evaluati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> sources, fate, andeffects; omissi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> stressors; and overlooking sec<strong>on</strong>dary effects (USEPA 1998). Thetypes <str<strong>on</strong>g>of</str<strong>on</strong>g> uncertainties that are associated with the c<strong>on</strong>ceptual model used to linkc<strong>on</strong>taminant sources to effects <strong>on</strong> <strong>Fraser</strong> <strong>River</strong> sockeye salm<strong>on</strong> include those associatedwith the identificati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> chemicals <str<strong>on</strong>g>of</str<strong>on</strong>g> potential c<strong>on</strong>cern, envir<strong>on</strong>mental fate and transport<str<strong>on</strong>g>of</str<strong>on</strong>g> these chemicals, and exposure pathways.Identificati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> chemicals <str<strong>on</strong>g>of</str<strong>on</strong>g> potential c<strong>on</strong>cern represents an important source <str<strong>on</strong>g>of</str<strong>on</strong>g>uncertainty in the c<strong>on</strong>ceptual model for the <strong>Fraser</strong> <strong>River</strong> Basin. In this study, an Inventory<str<strong>on</strong>g>of</str<strong>on</strong>g> Aquatic <str<strong>on</strong>g>C<strong>on</strong>taminants</str<strong>on</strong>g> was developed using informati<strong>on</strong> <strong>on</strong> the sources and releases <str<strong>on</strong>g>of</str<strong>on</strong>g>chemicals <str<strong>on</strong>g>of</str<strong>on</strong>g> potential c<strong>on</strong>cern based <strong>on</strong> the land-uses which comprise the <strong>Fraser</strong> <strong>River</strong>Basin. Informati<strong>on</strong> <strong>on</strong> land and water uses in the <strong>Fraser</strong> <strong>River</strong> Basin was acquired frommany sources and verified using the results <str<strong>on</strong>g>of</str<strong>on</strong>g> an independent analysis c<strong>on</strong>ducted by Nelitzet al. (2010). As such, it is likely that the majority <str<strong>on</strong>g>of</str<strong>on</strong>g> potential sources <str<strong>on</strong>g>of</str<strong>on</strong>g> chemicals <str<strong>on</strong>g>of</str<strong>on</strong>g>121

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