Downriggin -
I understand where you are coming from. I don't think anyone has all the answers; know that I certainly don't.

For much of the 1980s and 1990s the Puget Sound herring stocks were down howevert they seem to be rebounding (especially the mid/south stocks) Regarding the pen released hatchery fish - two thoughts. If your scenario were correct then the wild fish (unmarked) would be larger - all the enhancement fish (those paid for by the sure charge and held longer) are marked prior to release. Don't believe that is the case. Also if food was as abundant in the Sound then the ocean coho would not be larger than the Sound fish.

A thought I have had regarding the apparent higher productive of the ocean may be due to more upwellings on the coast than in the Sound. Those upwellings tend to bring nutrients to the surface thus stimulating the food chain. I'm not an oceanographer so others may be able to correct my thinking.

Tight lines
Smalma