REGIONAL— The Minnesota Department of Health, or MDH, has released updated fish consumption advisories, with revisions geared specifically for lakes in northeastern Minnesota. The new Northeast Fish Consumption Guidelines, released this past week, apply to most lakes in St. Louis, Lake, and Cook counties and reflect the fact that fish in many Arrowhead lakes contain more methylmercury than is found in fish elsewhere in the state.
The stricter guidelines apply to both sensitive individuals as well as the general public. The guidelines are significantly stricter for sensitive, which includes children under age 15 and girls or women over 15 who are pregnant, may become pregnant, or who are breast feeding or may breast feed in the future.
While health officials stress that consuming fish is an important part of a healthy diet, mercury levels in some fish is higher than is recommended, and that is particularly true in northeastern Minnesota, although levels vary significantly from lake to lake. Mercury is a toxic chemical that impacts the kidneys, liver, and nervous system. Growing fetuses, infants, and young children are the most sensitive to the effects of mercury, which can negatively impact understanding and learning in young children. Fish absorb mercury, specifically methylmercury, from their food, where it then binds to proteins in the fish tissue. Over time, fish can accumulate relatively high mercury concentrations, and that’s particularly true of larger top predator fish like walleye, northern pike, bass, and muskie.
For the general public, the new northeastern Minnesota guidelines apply to lakes or streams not covered by a specific guideline. Some lakes that are known to be especially high in mercury, like Crane Lake, have their own consumption guidelines that are stricter than the newly issued recommendations, and those recommendations still apply. Anglers can determine which lakes have specific guidelines using the DNR’s Lakefinder tool, which has a link to the guidelines in effect for individual lakes.
The new general guidelines for the Arrowhead have a number of differences from those that cover lakes in the rest of the state. For the general public, the guidelines now recommend just two servings of crappie or sunfish per week, or just one serving of yellow perch. In the rest of the state, the MDH says that anglers can eat up to four servings of those same fish every week. For other species, like walleye, northern pike, lake trout, or bass, the guidelines recommend just one serving per week.
For sensitive individuals, the new general Arrowhead guidelines recommend no more than one serving per week of locally-caught crappie, sunfish, trout, whitefish, or herring, and only one serving per month of species like walleye (under 18 inches), yellow perch, lake trout, or northern pike (under 26 inches).
The MDH notes that larger fish tend to have higher concentrations of mercury in their flesh, which is why the guidelines encourage the public to consume smaller-sized fish. That trophy walleye makes a good photograph and a story to tell, but the smart angler is putting it back in the lake.
The new updated guidelines are based on an improved understanding of the effects of mercury on sensitive populations, rather than an increase in mercury levels in fish in Arrowhead lakes. The guidelines are based on additional testing data as well, including the results of over 43,000 fish samples from nearly 1,400 lakes tested across the state since 1967.
The MDH was concerned that the general statewide guidelines, which previously applied to lakes in the Arrowhead where no mercury testing had been done, may not be protective enough of sensitive populations in the region. Recent studies of blood from infants in the Great Lakes region found that those within the Lake Superior basin have higher levels of mercury than is considered safe.
The Timberjay contacted the Minnesota Pollution Control Agency to learn more about the sources of higher mercury levels in northeastern Minnesota fish, but the agency did not provide answers to specific questions.
Instead, an agency spokesperson provided an excerpt from the agency’s website, stating that “Mercury pollution from outside the state affects Minnesota, and mercury concentrations in fish have not significantly declined despite emissions reductions in North America. However, while we’re seeing global increases in mercury emissions, ambient air mercury concentrations across the United States have fallen due to federal and state regulatory actions and market forces, indicating that local mercury reductions are still important.”
The MPCA has been working for over two decades to reduce the amount of mercury in the environment. While it has made considerable progress, reducing statewide emissions or other discharges from about 3,300 pounds annually in 2005 to about 1,100 pounds in 2025, that still missed the agency’s goal of reaching 789 pounds by last year. While most industrial sectors have made remarkable reductions, the taconite industry has been a notable exception. The industry now accounts for over 50 percent of mercury emissions in the state, as the industry has achieved little in the way of reduction over the past 20 years while most other sectors have achieved relatively dramatic reductions.
Even so, the MPCA contends that the majority of mercury that falls in the state’s watersheds, typically through rain or snow, comes from national or global sources. It is worth noting, however, that the majority of the lakes experiencing high mercury levels are located in northeastern Minnesota, where the state’s taconite operations are located.
Additional information about mercury and health can be found on MDH’s website: Contaminants and Minnesota Fish.