Researchers Release New Data on Walleye Methylmercury Contamination

Feb. 7, 2008
Data could help Ojibwe tribal members avoid methylmercury consumption

A group of researchers has produced new data and advice for the Ojibwe tribal members in the northern Great Lakes region who harvest walleye, a fish that commonly has harmful concentrations of methylmercury. The results are published in the latest issue of Integrated Environmental Assessment and Management.

Walleye are at the top of the aquatic food chain, typically accumulating mercury in their tissues to potentially dangerous levels. Leading this study, the Great Lakes Indian Fish and Wildlife Commission (GLIFWC) has produced walleye consumption advisories depicted on maps since 1996 to help tribal members reduce exposure to methylmercury due to fish consumption.

In creating updated advisories, however, the GLIFWC was careful to balance the risks of walleye consumption with the clear health benefits of eating fish. The harvest and consumption of fish are culturally important activities of the Ojibwe tribes. Walleye harvest has increased since the 1980s when federal courts reaffirmed the tribes’ rights to hunt, fish, and gather in territories ceded to the United States through treaties signed in 1837 and 1842 in the present-day states of Michigan, Minnesota and Wisconsin.

The new data, collected through a risk-based approach, provides consumption advice for 293 of the 449 lakes assessed in the region. Most of the advisories for the lakes carry a recommendation of no more than four meals per month for the general population and no more than one meal per month for the sensitive population. The approach used here could be adapted for other regions. To read the entire study, visit 3793-4-1-118.pdf.

Source: Society of Environmental Toxicology and Chemistry