Potential Effects of Contaminants on Fraser River Sockeye Salmon

<strong>Contaminants</strong> <strong>of</strong> emerging concern are likely to be released to surface waters fromnumerous point source and non-point source discharges that are primarily located alongthe migration corridors for sockeye salmon. As was the case for endocrine disruptingcompounds, it is assumed that the magnitude and duration <strong>of</strong> exposure to thesecontaminants originating from municipal and industrial sources are high for up-river stockswith the longest migration distances (i.e., those returning to the Quesnel, Bowron, andNechako river watersheds), moderate for stocks with intermediate migration distances(i.e., those returning to the Chilko, Seton-Portage, and Thompson river watersheds), andlow for stocks with the shortest migration distances (i.e., those returning to the Pitt,Harrison, and Cultus river watersheds).6.2.5 <strong>Potential</strong> Risks to Sockeye Salmon Associated with Exposure to<strong>Contaminants</strong> <strong>of</strong> Emerging Concern in the Fraser River BasinDue to the general paucity <strong>of</strong> toxicity and exposure data, it is difficult to evaluate the risksto sockeye salmon associated with exposure to contaminants <strong>of</strong> emerging concern in theFraser River Basin. Nevertheless, Johannessen and Ross (2002) used the results <strong>of</strong> adetailed review <strong>of</strong> the available data and information to classify contaminants into fourgroups (high risk, moderate risk, low risk, and unknown) based on their potential toadversely affect late-run sockeye salmon in the Fraser River Basin. The contaminants <strong>of</strong>emerging concern that fell into each <strong>of</strong> these categories included:<strong>Contaminants</strong> Posing High Risk - The following substances were considered to posethe highest risk to late-run sockeye salmon in the Fraser River Basin. Suchcontaminants are the most likely to be contributing, along with other factors (such asoceanographic conditions, disease, and water temperatures during upstreammigration), to the decline <strong>of</strong> sockeye salmon in the study area:• Pesticides (metam and chlorothalonil; Rationale: Use <strong>of</strong> these substances isincreasing in the Fraser River Basin and its use is correlated with reductions insockeye salmon abundance);• Polybrominated diphenylethers (PBDEs; Rationale: Levels are rapidlyincreasing in the environment and these substances are known endocrinedisruptors);• Phthalate esters (Rational: Ubiquitous distribution in the environment, knownendocrine disruptors, and potentially toxic to fish); and,109