Just a question here, not an opinion.
This is old memory time only:
Something tickles the back of my mind on why the Salmon/Steelhead were introduced into the Great Lakes. Remember something about one, or more, of the lakes being over run with a small fish (Alwaies, or something like that). Huge numbers would die and wash up on the beaches.
The salmon/steelhead were planted as an experiment to control the population(s) of these fish. It worked.