Fish Contaminants

I’m wondering if anyone else paid attention to this small article in the recent OOD.
“Poisoned angler calls for better access to information”.
There are a few more details in the CBC article.
https://www.cbc.ca/news/canada/thund...hted-1.5904772
I was always thinking about this problem. As this guy, Jason Doyon, I was also thinking that this is kind of BS. Now it seems that we have clear evidence that this is a real problem.
But what I never could get is where these contaminants, mercury, PCB and other, come from. The strange thing is that any lake you get, close to human development or very far remote, there are still some contaminants. Meaning that the level of mercury and other stuff is not human related, but belongs to nature natively.
And even more strange. For example, Lake Aquitaine in Mississauga, very close to my house, is full of garbage and other , but… you can still eat fish from this cesspool in the same amount as from remote lakes or Georgian Bay. … Oh, I just checked it out! Actually not! From Aquitaine you can eat Common Carp 24’’ long 16 times in a month while from GB only once.
That really doesn’t make sense to me. How could it be?
And then: what about the fish we buy in the stores? This fish may come from the same waters. And there is no advisory table on how much you can eat.
Any thoughts on that?

I just read... There are some thoughts about the issue in this thread
https://www.oodmag.com/community/sho...436-Smelt-runs

Yes, very interesting..
https://www.sootoday.com/local-news/...es-why-3581088
Smelt is the worst fish to eat. It is the most contaminated fish. But this is also fish which all other bigger-size species feed on. So, logically, these whitefish, trout, salmon etc. should be even worse. … But not… Doesn’t make sense to me again...