Mercury in fish tissue

We look at the amount of mercury in edible tissue from freshwater fish to understand if contamination levels are changing. We monitor mercury because it persists in the environment, accumulates in the tissues of fish and humans, and is toxic in large concentrations.

We monitor mercury to protect health

We worked with the state Department of Health to develop a Chemical Action Plan (CAP) for mercury in 2003. The plan details natural and human-caused sources, identifies the way mercury moves through the environment, summarizes health effects, and discusses fish consumption advisories.

We've supported the CAP by assessing mercury in fish tissue every year since 2005. Each year, we collect 10 individual largemouth or smallmouth bass from six waterbodies to analyze total mercury accumulation. We return to each set of waterbodies every five years to assess trends.

Analyzing samples and preparing reports takes two to three years from time of sampling. Our latest report from statewide monitoring is from the 2016 sampling year. For other reports, see specific sampling locations in the map below or the Fish Toxics publications page.
Our data provide the state Department of Health with information to offer guidance on which fish and how much fish can be safely eaten under specific circumstances. We are also learning more about what happens to mercury in the environment. The EIM Study ID for this project is "HgFish."