The State of Michigan publishes a Guidebook in an attempt to address those concerns.
It is pretty well put together. It defines portion size in a realistic and usable manner.
|These portion sizes are generous compared to what you see in most dieting books but I think they are very realistic when you look at the amounts that people actually put on their plates.|
and it provides defaults to keep it manageable
One way to sort it out is that if you usually catch your fish with worms on a #8 hook, then you can eat eight servings a month. If you catch them with small minnows on a #6 hook they you are limited to six servings a month.
Carp are an exception because they vacuum up everything in the path, live a long time and get huge. You are allowed fewer servings of carp. This does not square with how Europeans eat carp. They turn up their noses at any carp that are larger than 2.2 pounds as not edible.
|Here are one of the recommendations specific to Eaton county. You can see that Carp are not recommended and that the limit for Suckers is one quarter of the default.|
The guide also lists major bodies of water for each county. Some bodies of water, like the Kalamazoo river, are DO NOT EAT due to various types of contamination. Other watersheds are broken down by stretches based on historical risk of contamination and varying test results.