The link below is great resource for those who love to fish in Michigan rivers. Check page 67 to see which Shiawassee River fish you can safely eat and how often.

https://www.michigan.gov/-/media/Project/Websites/mdhhs/Folder2/Folder70/Folder1/Folder170/MDCH_EAT_SAFE_FISH_GUIDE_-_SOUTHEAST_MI_WEB.pdf?rev=1226fe9fe87c43d0b24ba48ee5423b88