Here’s a scenario. You catch a brook trout in a seemingly clear and clean stream. There is no industry to speak of, but the stream is open to Great Lakes salmon that come up and spawn and die in the fall.
What are the chances of that brook trout being contaminated with nasty chemicals? The answer is they just might be, according to a story in Science Daily today that reports on University of Notre Dame research that found that the unintended consequences of allowing Great Lakes migratory fish to pass upstream can be a transfer of the contamination from salmon to say, a brook trout – and your dinner.
Salmon accumulate a variety of toxic chemicals during their stay in the Great Lakes, particularly near big urban centers. Those chemicals are left behind upstream in both their rotting bodies after death and in their eggs which brook trout eat.
As Michigan moves ahead with dam removal projects on Great Lake tributaries like the Boardman River, this is an issue that will come into ever-sharper focus. And it should. As the story suggests, we have fish consumption advisories for salmon, but not for stream fish.
What is safe and how many and how often? Those questions are likely to come up more and more. Read more: Migrating Toxics in Fish