It took us 150 years of harvesting salmon commercially, recreationally, and otherwise to our hearts content to deplete the populations to the levels that they are at today.... and still today we continue to harvest fish for the table although with more oversight than the past...

Why the hell anyone would think it would take any LESS than 150 years to bring the runs back (naturally) to where they once were is beyond me.
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When I grow up I want to be,
One of the harvesters of the sea.
I think before my days are done,
I want to be a fisherman.