The Michigan Department of Health & Human Services (MDHHS) publishes advisories about consumption of fish from various lakes and streams in Michigan.
(Throughout the websites and brochures cited in this post, any mention of MDCH, the Michigan Department of Community Health, refers to one of MDHHS’ predecessor agencies.)
The Michigan Eat Safe Fish Guide says (p. 71):
Chemicals that cause Michigan’s Eat Safe Fish guidelines are DDT, dioxins, mercury, PCBs, PFOS, selenium, and toxaphene. A lot of these chemicals were put into our environment before we knew the long-term problems these chemicals caused.
Even though many of these chemicals are no longer used, they still remain in our environment. These chemicals can travel through the air and be carried by rain run-off and storm drains into our lakes, rivers, and wetlands. Once these chemicals are in the water, they sink to the bottom and become a part of the fish food chain.
Generally, the older and bigger that fish get, the more contaminated they are. Also, a lot depends on the species, the water body, how you clean the fish and how you cook it.
The MDHHS guide for southeast Michigan waters has separate sections for 17 counties, Lake Huron and Lake Erie, plus information about many other lakes and streams in the region.
Note especially, that the state recommends that you eat nothing caught in the South Branch of the Shiawassee River because of PCB contamination. The same applies to the Lange and Revere canals on Lake St. Clair. Indeed, the state urges more strict limitations on consumption of fish caught within two miles of the Lange and Revere canals than in Lake St. Clair generally.
Musky taken from Lake St. Clair shouldn’t be eaten. Ditto for carp and catfish in Saginaw Bay.
In most locations, more servings per month of panfish are approved than larger fish.