Foregone Opportunity. If you don't catch them we will because any fish above the escapement goal is both wastage and leads to catastrophic over escapement that will destroy the runs.

If there is either a designated "harvestable number" or a designated "impact number" it will be killed. Not fishing just gives it to the other side.

Had a situation on Skagit Chinook where the cowboys had something like 75 fish left in the 50:50 share. Proposed to just leave them alone, tribes fish to their identified number. Nope, we were told. If those fish are on the computer, they will be fished for. So, there was a one-night cowboy gill net fishery in Skagit Bay in the 80s.