Excuse my ignorance, but I have not ran into any "marked" blackmouth.

This could partially be due to the fact that:
I winter fished this year for the first time in several years, and/or my winter fishing experience is limited to a couple areas - Saratoga Passage and Oak Bay.

By "marked" do you mean adipose clipped? What part of the sound are you catching the "marked" chinook?

Other questins I have always wondered are:
Do "Blackmouth" head out to sea the following year? If there is a blackmouth season now, like there appears to be in some parts of the sound, are the fish bigger than the ones I catch in January/February? Why are blackmouth always around 6 - 9 lbs?

Ate the last one from the freezer Monday night.

Thanks