Mercury in Sportfishes of Lake Whatcom, Washington, Including a Review of Potential Impacts to Aquatic Resources and People

Several tissue samples (n = 273) representing seven species of edible sportfish from Lake Whatcom were analyzed for total mercury content in late spring 2000. Predaceous smallmouth bass (Micropterus dolomieu) displayed the highest levels of mercury (mean ± SE, range = 0.49 ± 0.03, 0.10 â€" 1.84 mg/kg), followed by omnivorous yellow perch (Perca flavescens) (0.20 ± 0.03, 0.05 â€" 0.87 mg/kg) and brown bullhead (Ameiurus nebulosus) (0.16 ± 0.06, 0.03 â€" 0.79 mg/kg), planktivorous kokanee (Oncorhynchus nerka) (0.12 ± 0.01, 0.07 â€" 0.25 mg/kg), herbi-detritivorous signal crayfish (Pacifasticus leniusculus) (0.11 ± 0.02, 0.03 â€" 0.54 mg/kg), and benthivorous pumpkinseed (Lepomis gibbosus) (0.10 ± 0.01, 0.03 â€" 0.28 mg/kg). Predaceous cutthroat trout (Oncorhynchus clarki) had the lowest levels (0.07 ± 0.01, 0.03 â€" 0.20 mg/kg), possibly related to the low trophic level of the smaller size classes captured, natal stream residency of wild fish, or hatchery origins of stocked fish. Interbasin differences in mercury concentrations were evident in all species sampled. The mean levels found in Basin 3 (south) were higher than those from Basins 1 or 2 (north). Our results are compared with levels found in other North American fish populations, both near known pollution sources and away from anthropogenic influence. A literature review provides insight into possible population-level consequences (i.e., fish health concerns), trophic links from blue-green algae to higher order vertebrates, and human health concerns. To this end, our results are related to a range of values representing state, federal, and international screening levels for the contaminant.