Minnesota fish, good for you in moderation

There's nothing quite like a sunny day on the lake when the fish are biting.  When you add in an evening fish fry of the catch of the day, it's a perfect Minnesota summer night. 

Fish are an excellent source of low fat protein and the omega-3 fatty acids that we hear so much about these days.  The MN Food & Drug Administration says that omega-3 fatty acids may reduce the risk of coronary heart disease.  Omega-3 fatty acids are essential for human health, but are not manufactured by our bodies so we need to get them from food.

Although there are many healthy benefits to eating fish, there are also contaminants found in the fish in Minnesota lakes.  Mercury can be harmful to our health, especially the health of children and developing fetuses.  It is a neurotoxin that causes learning and developmental disabilities in children.

Most Mercury comes from the air.  Mercury gets into the air through emissions from coal-burning plants and taconite processing and moves long distances in the wind currents.  From there, it settles into our lakes and streams and bacteria convert it to a toxic form, methylmercury.  The problem is that 90% of the mercury in our waters comes from other states and countries, which is why it is so hard to regulate.  In turn, 90% of the mercury emitted in Minnesota goes to other states and countries. 

The mercury that settles into our lakes and streams gets filtered by zooplankton, the tiny animals that get eaten by small fish.  The larger the small fish gets, the more mercury builds up in it's tissue from all the zooplankton eaten.  Mercury bioaccumulates, which means that at each step in the food chain the mercury builds to higher levels, especially in large predatory fish such as walleye, northern pike and muskies (bioaccumulation).

The Minnesota Department of Health and the Pollution Control Agency have done studies on the amount of mercury in our lakes and have set safe eating guidelines for our fish.  In general, men and non-pregnant women can eat an unlimited amount of sunfish, crappie, perch and bullheads.  When eating walleyes, northern pike, smallmouth bass and largemouth bass, it's safe to limit yourself to one meal a week.  Pregnant women and children under 15 should limit themselves to 1 meal a week of sunfish crappies, perch and bullheads and one meal a month of walleyes shorter than 20 inches, northern pike shorter than 30 inches, smallmouth bass and largemouth bass.  Pregnant women and children should not eat walleyes larger than 20 inches and northern pike longer than 30 inches.

Each lake that has been evaluated by the MPCA has its own specific guidelines for fish caught within its waters.  To find the guidelines for your lake, you can visit the DNR Lakefinder at: http://www.dnr.state.mn.us/lakefind/index.html.  If your lake does not have specific guidelines that may just mean that it has not been individually evaluated.  Those lakes should follow the general guidelines listed above.   The following lakes in Becker County are on the 2006 Impaired Waters list for high mercury: Straight, Two Inlets, Boot, Bad Medicine, Toad, Many Point, Elbow, Cotton, Strawberry, White Earth, Sallie, Muskrat, Detroit, Little Floyd, Floyd, Big Cormorant, and Ida.

This article is not meant to scare you into not eating Minnesota fish anymore!  Just make sure you follow the guidelines created by the MDH and PCA.  Also, remember that small fish have generally less mercury than large fish.  Large fish, such as walleyes over 20 inches, don't actually taste as good as the small fish anyway.  It is better for our health and for the health of our lakes to follow slot limits and practice catch and release.

Until next week, enjoy the lakes!

Moriya Rufer is the Lakes Monitoring Program Coordinator for RMB Environmental Laboratories in Detroit Lakes, 218-846-1465, lakes.rmbel@eot.com.