Buyer, fisherman, and consumer beware… Minnesota fish may not be as safe to eat as you think. I recently posted a blog that contained information about a study that was conducted by the USGS stating that mercury levels on Minnesota lakes may not be dropping as quickly as once thought, but the fish are still safe to eat. Unfortunately, that conclusion may not be entirely accurate. Mark Brigham, a hydrologist for the USGS reached out to me and wanted to clarify some facts about our beloved lakes and the fish that are in them.
Voyageur National Park Courtesy of David P Krabbenhoff
The original study focuses on 4 different lakes in Voyageurs National Park in northern Minnesota and how much mercury is still left in the lakes. 2 lakes showed a consistent drop in mercury levels since 1998 while another lake showed a significant increase and a fourth lake showed no consistency either way. The conclusion of the study suggested that the existence of mercury in area waterways may be far more complicated than once thought and obviously more research is needed before any true conclusions can be made.
The original study can be seen here: http://toxics.usgs.gov/highlights/mercury_deposition.html
Mercury is something that many of us have known, including this meteorologist, to come from pesticides. But it turns out that the main source of mercury in our water doesn’t actually come from pesticides, especially in these remote northern Minnesota lakes. Mr Brigham states, “Mercury has historically been used in pesticides and seed coatings for crop seeds, this is not the primary source of mercury to the environment and particularly not to the remote lakes in Voyageurs National Park. Other research has shown that in northern Minnesota, the mercury enters lake ecosystems predominantly from atmospheric deposition. About one third of the atmospheric mercury is from natural sources; and two thirds is anthropogenic, resulting from industrial activities. At present, coal combustion is the largest component of anthropogenic mercury in the U.S., although numerous other sources emit mercury to the atmosphere. As of 1990, municipal waste incinerators and medical waste incinerators were also large sources, due to the many mercury-containing products that ended up in the waste stream. That source has largely been eliminated in the U.S., leaving coal as a primary culprit. Domestic emissions have decreased considerably since 1990, although mercury emissions in Asia--and worldwide--have increased.”
Because of this, Mr. Brigham goes on to state that fish consumption advisories are nothing new to the state of Minnesota… something that I was completely unaware of because unlike most Minnesotans, I’m not much of a fisherman. He states, “There is a concern for people who consume fish regularly--particularly young children and women of child-bearing years. The Minnesota Department of Health issues fish consumption advisories on many of Minnesota's lakes and rivers, suggesting that people limit consumption of fish. The specific advisories depend on the amount of mercury measured in those fish. For nearly all water bodies in the state, some level of fish consumption is acceptable, but that's not to say they're entirely safe. Some advisories suggest consumption of no more than one meal per month. Almost all of Minnesota's fish consumption advisories are due to mercury.”
To view current fish consumption advisories for Minnesota lakes… you can go to the Minnesota DNR website by clicking this link: http://www.dnr.state.mn.us/lakefind/index.html
Just having a quick peek at some of the advisories on current Minnesota lakes has me second guessing my current fish intake, even though they are a really good source of Omega 3’s and protein… both necessary for maintaining good health.
The take away message?? Don’t stop eating area fish altogether, that would just be a knee jerk reaction. But just like every other aspect of life, research what you are putting in your body and know for sure that it is safe for consumption. This is something that we need to continue to do regardless of our food source. When it comes to mercury levels though, this may be a topic we continue to hear about for a long time to come because “Mercury can travel long distances in the atmosphere before being deposited to the earth. With mercury emissions generally decreasing in the U.S. and Canada, but increasing in Asia, it will be important to continue to stay on top of the issue for some time.”