Having been in the managing and accounting circus there are some reasons for the assumptions made. First, it is way too expensive to monitor the daily catch for composition. And it can change daily.

Boldt (pre-ESA) complicated things by requiring sharing. As a consequence, managers were forced to make assumptions. These, at the 5,000' level, made sense. At the actual daily level, on the ground, it doesn't.

We know, for example, that Hood Canal chum are in the east Kitsap Bays. They get accounted as South Sound. If you wanted to account for them as HC you would make significant changes in the fisheries.

ESA put another wrench in, as tagging shows distribution and the occasional listed fish shows up in odd places. For example, smolts tagged in Duwamish (steelhead) were captured as adults in the Columbia. Should the Columbia be managed for Duwamish ESA needs.

Stock distributions are way more complex in time and space than out desire to fish the ocean will allow.