Spatiotemporal variation in fish mercury contamination: Comparing approaches for crafting consumption advisories and...

Mercury in fish is a serious human health concern. Mercury is a widespread contaminant that exceeds health effect thresholds in many fish species and waterbodies. The objectives were to determine the spatiotemporal variation of mercury in fish tissue for several fish species across thousands of lakes and to assess the potential use of fish length standardization and statistical models to improve fish consumption guidelines and impairments determinations in lake-rich areas. The results showed that fish length, species, ecoregion, lake size, latitude, color dissolved organic matter, water clarity, and zebra mussel presence influenced mercury concentrations. Fish mercury concentrations were generally higher from 1967 to 1990, and since 1990 there was no obvious trend. We found that a statistical model provided estimates of mean mercury concentrations by fish total length that were unbiased and with greater confidence than those based solely on sample statistics. The use of fish length standardization and inclusion of predictive models could improve precision and consistency of fish consumption guidelines and impairments determinations.